diff --git a/CHANGELOG.md b/CHANGELOG.md
index fd173d97..d6fa4508 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -68,6 +68,7 @@ Users may have to change how they access the system
 
 ### Minor features
 
+* JSON errors are now labelled with JSON and not XML
 * Restconf native HTTP/2:
   * Added option `CLICON_RESTCONF_HTTP2_PLAIN` for non-TLS http
     * Default disabled, set to true to enable HTTP/2 direct and switch/upgrade HTTP/1->HTTP/2
@@ -78,6 +79,7 @@ Users may have to change how they access the system
 
 ### Corrected Bugs
 
+* Fixed: [Performance issue when parsing large JSON param](https://github.com/clicon/clixon/issues/266)
 * Fixed: [Duplicate lines emitted by cli_show_config (cli output style) when yang list element has composite key](https://github.com/clicon/clixon/issues/258)
 * Fixed: [JSON leaf-list output single element leaf-list does not use array](https://github.com/clicon/clixon/issues/261)
 * Fixed: Netconf diff callback did not work with choice and same value replace
diff --git a/apps/cli/cli_auto.c b/apps/cli/cli_auto.c
index fe33128a..7b0cce6b 100644
--- a/apps/cli/cli_auto.c
+++ b/apps/cli/cli_auto.c
@@ -521,6 +521,7 @@ cli_auto_up(clicon_handle h,
     char    *api_path = NULL;
     int      i;
     int      j;
+    size_t   len;
     
     if (cvec_len(argv) != 1){
 	clicon_err(OE_PLUGIN, EINVAL, "Usage: %s(<treename>)", __FUNCTION__);
@@ -551,7 +552,8 @@ cli_auto_up(clicon_handle h,
     /* Find diff of 0 and 1 (how many variables differ?) and trunc cvv0 by that amount */
     cvv0 = clicon_data_cvec_get(h, "cli-edit-cvv");
     j=0; /* count diffs */
-    for (i=strlen(api_path_fmt1); i<strlen(api_path_fmt0); i++)
+    len = strlen(api_path_fmt0);
+    for (i=strlen(api_path_fmt1); i<len; i++)
 	if (api_path_fmt0[i] == '%')
 	    j++;
     cvv1 = cvec_new(0);
diff --git a/apps/cli/cli_common.c b/apps/cli/cli_common.c
index 41b4802d..fc75c9a1 100644
--- a/apps/cli/cli_common.c
+++ b/apps/cli/cli_common.c
@@ -1210,6 +1210,7 @@ cli_copy_config(clicon_handle h,
     char        *toname;
     cxobj       *xerr;
     cvec        *nsc = NULL;
+    size_t       len;
 
     if (cvec_len(argv) != 6){
 	clicon_err(OE_PLUGIN, EINVAL, "Requires 6 elements: <db> <xpath> <namespace> <keyname> <from> <to>");
@@ -1241,8 +1242,9 @@ cli_copy_config(clicon_handle h,
 	goto done;
     }
     /* Sanity check that xpath contains exactly two %s, ie [%s='%s'] */
+    len = strlen(xpath);
     j = 0;
-    for (i=0; i<strlen(xpath); i++){
+    for (i=0; i<len; i++){
 	if (xpath[i] == '%')
 	    j++;
     }
diff --git a/apps/cli/cli_generate.c b/apps/cli/cli_generate.c
index ee170005..8e777750 100644
--- a/apps/cli/cli_generate.c
+++ b/apps/cli/cli_generate.c
@@ -404,6 +404,7 @@ yang2cli_var_sub(clicon_handle h,
     int           j;
     char         *cvtypestr;
     char         *arg;
+    size_t       len;
 
     if (cvtype == CGV_VOID){
 	retval = 0;
@@ -428,7 +429,8 @@ yang2cli_var_sub(clicon_handle h,
 		    cprintf(cb, "|"); 
 		/* Encode by escaping delimiters */
 		arg = yang_argument_get(yi);
-		for (j=0; j<strlen(arg); j++){
+		len = strlen(arg);
+		for (j=0; j<len; j++){
 		    if (index(CLIGEN_DELIMITERS, arg[j]))
 			cprintf(cb, "\\");
 		    cprintf(cb, "%c", arg[j]); 
diff --git a/apps/restconf/restconf_lib.c b/apps/restconf/restconf_lib.c
index 7cb1b1d3..1384aee0 100644
--- a/apps/restconf/restconf_lib.c
+++ b/apps/restconf/restconf_lib.c
@@ -287,6 +287,7 @@ restconf_convert_hdr(clicon_handle h,
     cbuf         *cb = NULL;
     int           i;
     char          c;
+    size_t       len;
     
     if ((cb = cbuf_new()) == NULL){
 	clicon_err(OE_UNIX, errno, "cbuf_new");
@@ -294,7 +295,8 @@ restconf_convert_hdr(clicon_handle h,
     }
     /* convert key name */
     cprintf(cb, "HTTP_");
-    for (i=0; i<strlen(name); i++){
+    len = strlen(name);
+    for (i=0; i<len; i++){
 	c = name[i] & 0xff;
 	if (islower(c))
 	    cprintf(cb, "%c", toupper(c));
diff --git a/apps/restconf/restconf_methods_patch.c b/apps/restconf/restconf_methods_patch.c
index dfa8e066..98e963c4 100644
--- a/apps/restconf/restconf_methods_patch.c
+++ b/apps/restconf/restconf_methods_patch.c
@@ -113,6 +113,7 @@ yang_patch_xml2json_modified_cbuf(cxobj *x_simple_patch)
     cbuf *cb = NULL;
     char *json_simple_patch_tmp;
     int   brace_count = 0;
+    size_t len;
 	
     json_simple_patch = cbuf_new();
     if (json_simple_patch == NULL)
@@ -122,7 +123,8 @@ yang_patch_xml2json_modified_cbuf(cxobj *x_simple_patch)
 
     // Insert a '[' after the first '{' to get the JSON to match what api_data_post/write() expect
     json_simple_patch_tmp = cbuf_get(cb);
-    for (int l = 0; l < strlen(json_simple_patch_tmp); l++) {
+    len = strlen(json_simple_patch_tmp);
+    for (int l = 0; l < strlen(len); l++) {
         char c = json_simple_patch_tmp[l];
         if (c == '{') {
             brace_count++;
diff --git a/lib/clixon/clixon_err.h b/lib/clixon/clixon_err.h
index 7f630073..a5cd9516 100644
--- a/lib/clixon/clixon_err.h
+++ b/lib/clixon/clixon_err.h
@@ -69,8 +69,8 @@ enum clicon_err{
     OE_UNIX,     /* unix/linux syscall error */
     OE_SYSLOG,   /* syslog error */
     OE_ROUTING,  /* routing daemon error (eg quagga) */
-    OE_XML,      /* xml parsing etc */
-
+    OE_XML,      /* xml parsing */
+    OE_JSON,     /* json parsing */
     OE_RESTCONF, /* RESTCONF errors */
     OE_PLUGIN,   /* plugin loading, etc */
     OE_YANG ,    /* Yang error */
diff --git a/lib/clixon/clixon_plugin.h b/lib/clixon/clixon_plugin.h
index 2d15531a..18e6dd25 100644
--- a/lib/clixon/clixon_plugin.h
+++ b/lib/clixon/clixon_plugin.h
@@ -206,6 +206,9 @@ typedef int (plgreset_t)(clicon_handle h, const char *db);
  */
 typedef int (plgstatedata_t)(clicon_handle h, cvec *nsc, char *xpath, cxobj *xtop);
 
+/* Transaction-data type
+ * @see clixon_backend_transaction.h for full transaction API 
+ */
 typedef void *transaction_data;
 
 /* Transaction callback */
diff --git a/lib/src/clixon_err.c b/lib/src/clixon_err.c
index ba49e879..d186d07d 100644
--- a/lib/src/clixon_err.c
+++ b/lib/src/clixon_err.c
@@ -116,6 +116,7 @@ static struct errvec EV[] = {
     {"Syslog error",           OE_SYSLOG},
     {"Routing demon error",    OE_ROUTING},
     {"XML error",              OE_XML},
+    {"JSON error",             OE_JSON},
     {"RESTCONF error",         OE_RESTCONF},
     {"Plugins",                OE_PLUGIN},
     {"Yang error",             OE_YANG},
diff --git a/lib/src/clixon_json.c b/lib/src/clixon_json.c
index 85aab8f7..41d0d65a 100644
--- a/lib/src/clixon_json.c
+++ b/lib/src/clixon_json.c
@@ -257,8 +257,10 @@ json_str_escape_cdata(cbuf *cb,
     int   retval = -1;
     int   i;
     int   esc = 0; /* cdata escape */
+    size_t len;
 
-    for (i=0;i<strlen(str);i++)
+    len = strlen(str);
+    for (i=0; i<len; i++)
 	switch (str[i]){
 	case '\n':
 	    cprintf(cb, "\\n");
@@ -372,7 +374,7 @@ json2xml_decode_identityref(cxobj     *x,
 	    /* Here prefix2 is valid and can be NULL
 	       Change body prefix to prefix2:id */
 	    if ((cbv = cbuf_new()) == NULL){
-		clicon_err(OE_XML, errno, "cbuf_new");
+		clicon_err(OE_JSON, errno, "cbuf_new");
 		goto done;
 	    }
 	    if (prefix2)
@@ -1245,7 +1247,7 @@ _json_parse(char      *str,
     if (clixon_json_parseparse(&jy) != 0) { /* yacc returns 1 on error */
 	clicon_log(LOG_NOTICE, "JSON error: line %d", jy.jy_linenum);
 	if (clicon_errno == 0)
-	    clicon_err(OE_XML, 0, "JSON parser error with no error code (should not happen)");
+	    clicon_err(OE_JSON, 0, "JSON parser error with no error code (should not happen)");
 	goto done;
     }
     /* Traverse new objects */
@@ -1361,7 +1363,7 @@ clixon_json_parse_string(char      *str,
 {
     clicon_debug(1, "%s", __FUNCTION__);
     if (xt==NULL){
-	clicon_err(OE_XML, EINVAL, "xt is NULL");
+	clicon_err(OE_JSON, EINVAL, "xt is NULL");
 	return -1;
     }
     if (*xt == NULL){
@@ -1422,18 +1424,18 @@ clixon_json_parse_file(FILE      *fp,
     int       len = 0;
 
     if (xt==NULL){
-	clicon_err(OE_XML, EINVAL, "xt is NULL");
+	clicon_err(OE_JSON, EINVAL, "xt is NULL");
 	return -1;
     }
     if ((jsonbuf = malloc(jsonbuflen)) == NULL){
-	clicon_err(OE_XML, errno, "malloc");
+	clicon_err(OE_JSON, errno, "malloc");
 	goto done;
     }
     memset(jsonbuf, 0, jsonbuflen);
     ptr = jsonbuf;
     while (1){
 	if ((ret = fread(&ch, 1, 1, fp)) < 0){
-	    clicon_err(OE_XML, errno, "read");
+	    clicon_err(OE_JSON, errno, "read");
 	    break;
 	}
 	if (ret != 0)
@@ -1454,7 +1456,7 @@ clixon_json_parse_file(FILE      *fp,
 	    oldjsonbuflen = jsonbuflen;
 	    jsonbuflen *= 2;
 	    if ((jsonbuf = realloc(jsonbuf, jsonbuflen)) == NULL){
-		clicon_err(OE_XML, errno, "realloc");
+		clicon_err(OE_JSON, errno, "realloc");
 		goto done;
 	    }
 	    memset(jsonbuf+oldjsonbuflen, 0, jsonbuflen-oldjsonbuflen);
diff --git a/lib/src/clixon_json_parse.y b/lib/src/clixon_json_parse.y
index d9db980c..019942c4 100644
--- a/lib/src/clixon_json_parse.y
+++ b/lib/src/clixon_json_parse.y
@@ -79,6 +79,7 @@ object.
 %union {
     int intval;
     char *string;
+    void *cbuf;
 }
 
 %token <string> J_FALSE
@@ -89,8 +90,8 @@ object.
 %token <string> J_CHAR
 %token <string> J_NUMBER
 
-%type <string>    string
-%type <string>    ustring
+%type <cbuf>      string
+%type <cbuf>      ustring
 %type <string>    number
 
 %lex-param     {void *_jy} /* Add this argument to parse() and lex() function */
@@ -102,7 +103,7 @@ object.
 /* typecast macro */
 #define _JY ((clixon_json_yacc *)_jy)
 
-#define _YYERROR(msg) {clicon_err(OE_XML, 0, "YYERROR %s '%s' %d", (msg), clixon_json_parsetext, _JY->jy_linenum); YYERROR;}
+#define _YYERROR(msg) {clicon_err(OE_JSON, 0, "YYERROR %s '%s' %d", (msg), clixon_json_parsetext, _JY->jy_linenum); YYERROR;}
 
 /* add _yy to error parameters */
 #define YY_(msgid) msgid 
@@ -150,7 +151,7 @@ void
 clixon_json_parseerror(void *_jy,
 		       char *s) 
 { 
-    clicon_err(OE_XML, XMLPARSE_ERRNO, "json_parse: line %d: %s at or before: '%s'", 
+    clicon_err(OE_JSON, XMLPARSE_ERRNO, "json_parse: line %d: %s at or before: '%s'", 
 	       _JY->jy_linenum ,
 	       s, 
 	       clixon_json_parsetext); 
@@ -265,7 +266,7 @@ value         : J_TRUE  { json_current_body(_JY, "true");       _PARSE_DEBUG("va
               | object                                        { _PARSE_DEBUG("value->object"); }
 	      | array                                         { _PARSE_DEBUG("value->array"); }
               | number  { json_current_body(_JY, $1); free($1); _PARSE_DEBUG("value->number");}
-              | string  { json_current_body(_JY, $1); free($1); _PARSE_DEBUG("value->string");}
+              | string  { json_current_body(_JY, cbuf_get($1)); cbuf_free($1); _PARSE_DEBUG("value->string");}
 
               ;
 
@@ -277,7 +278,7 @@ objlist       : pair             { _PARSE_DEBUG("objlist->pair");}
               | objlist ',' pair { _PARSE_DEBUG("objlist->objlist , pair");}
               ;
 
-pair          : string { json_current_new(_JY, $1);free($1);} ':' 
+pair          : string { json_current_new(_JY, cbuf_get($1));cbuf_free($1);} ':' 
                 value  { json_current_pop(_JY);}{ _PARSE_DEBUG("pair->string : value");}
               ;
 
@@ -292,19 +293,16 @@ valuelist     : value             { _PARSE_DEBUG("valuelist->value"); }
 
 /* quoted string */
 string        : J_DQ ustring J_DQ { _PARSE_DEBUG("string->\" ustring \"");$$=$2; }
-              | J_DQ J_DQ         { _PARSE_DEBUG("string->\" \"");$$=strdup(""); }
+              | J_DQ J_DQ         { _PARSE_DEBUG("string->\" \"");$$=cbuf_new(); }
               ;
 
 /* unquoted string: can be optimized by reading whole string in lex */
 ustring       : ustring J_CHAR 
                      {
-			 int len = strlen($1);
-			 $$ = realloc($1, len+strlen($2) + 1); 
-			 sprintf($$+len, "%s", $2); 
-			 free($2);
+			 cbuf_append_str($1,$2); $$=$1; free($2);
 		     }
               | J_CHAR 
-	             {$$=$1;} 
+	      { cbuf *cb = cbuf_new(); cbuf_append_str(cb,$1); $$=cb; free($1);} 
               ;
 
 number        : J_NUMBER { $$ = $1; }
diff --git a/lib/src/clixon_path.c b/lib/src/clixon_path.c
index b7127939..b8c8d4fd 100644
--- a/lib/src/clixon_path.c
+++ b/lib/src/clixon_path.c
@@ -460,13 +460,15 @@ api_path_fmt2api_path(const char *api_path_fmt,
     char   *str;
     char   *strenc=NULL;
     cg_var *cv;
+    size_t  len;
     
     if ((cb = cbuf_new()) == NULL){
 	clicon_err(OE_UNIX, errno, "cbuf_new");
 	goto done;
     }
     j = 1; /* j==0 is cli string */
-    for (i=0; i<strlen(api_path_fmt); i++){
+    len = strlen(api_path_fmt);
+    for (i=0; i<len; i++){
 	c = api_path_fmt[i];
 	if (esc){
 	    esc = 0;
@@ -546,13 +548,15 @@ api_path_fmt2xpath(char  *api_path_fmt,
     int     j;
     char   *str;
     cg_var *cv;
+    size_t  len;
 
     if ((cb = cbuf_new()) == NULL){
 	clicon_err(OE_UNIX, errno, "cbuf_new");
 	goto done;
     }
     j = 1; /* j==0 is cli string */
-    for (i=0; i<strlen(api_path_fmt); i++){
+    len = strlen(api_path_fmt);
+    for (i=0; i<len; i++){
 	c = api_path_fmt[i];
 	if (esc){
 	    esc = 0;
diff --git a/lib/src/clixon_regex.c b/lib/src/clixon_regex.c
index 73448bdc..6e6d8dd4 100644
--- a/lib/src/clixon_regex.c
+++ b/lib/src/clixon_regex.c
@@ -102,13 +102,15 @@ regexp_xsd2posix(char  *xsd,
     int   j; /* lookahead */
     int   esc;
     int   minus = 0;
-
+    size_t len;
+    
     if ((cb = cbuf_new()) == NULL){
 	clicon_err(OE_UNIX, errno, "cbuf_new");
 	goto done;
     }
     esc=0;
-    for (i=0; i<strlen(xsd); i++){
+    len = strlen(xsd);
+    for (i=0; i<len; i++){
 	x = xsd[i];
 	if (esc){
 	    esc = 0;
diff --git a/lib/src/clixon_string.c b/lib/src/clixon_string.c
index d6004a32..524bdaa4 100644
--- a/lib/src/clixon_string.c
+++ b/lib/src/clixon_string.c
@@ -250,7 +250,7 @@ uri_percent_encode(char **encp,
     char   *str = NULL;  /* Expanded format string w stdarg */
     char   *enc = NULL;
     int     fmtlen;
-    int     len;
+    size_t  len;
     int     i, j;
     va_list args;
 
@@ -276,8 +276,9 @@ uri_percent_encode(char **encp,
 	goto done;
     }
     memset(enc, 0, len);
+    len = strlen(str);
     j = 0;
-    for (i=0; i<strlen(str); i++){
+    for (i=0; i<len; i++){
 	if (uri_unreserved(str[i]))
 	    enc[j++] = str[i];
 	else{
@@ -311,7 +312,7 @@ uri_percent_decode(char  *enc,
     char *str = NULL;
     int   i, j;
     char  hstr[3];
-    int   len;
+    size_t len;
     char *ptr;
     
     if (enc == NULL){
@@ -325,8 +326,9 @@ uri_percent_decode(char  *enc,
 	goto done;
     }
     memset(str, 0, len);
+    len = strlen(enc);
     j = 0;
-    for (i=0; i<strlen(enc); i++){
+    for (i=0; i<len; i++){
 	if (enc[i] == '%' && strlen(enc)-i > 2 && 
 	    isxdigit(enc[i+1]) && isxdigit(enc[i+2])){
 	    hstr[0] = enc[i+1];
@@ -386,6 +388,7 @@ xml_chardata_encode(char      **escp,
     int     i, j;
     int     cdata; /* when set, skip encoding */
     va_list args;
+    size_t  slen;
     
     /* Two steps: (1) read in the complete format string */
     va_start(args, fmt); /* dryrun */
@@ -404,7 +407,8 @@ xml_chardata_encode(char      **escp,
     /* Step (2) encode and expand str --> enc */
     /* First compute length (do nothing) */
     len = 0; cdata = 0;
-    for (i=0; i<strlen(str); i++){
+    slen = strlen(str);
+    for (i=0; i<slen; i++){
 	if (cdata){
 	    if (strncmp(&str[i], "]]>", strlen("]]>")) == 0)
 		cdata = 0;
@@ -440,7 +444,8 @@ xml_chardata_encode(char      **escp,
 
     /* Same code again, but now actually encode into output buffer */
     j = 0; cdata = 0;
-    for (i=0; i<strlen(str); i++){
+    slen = strlen(str);
+    for (i=0; i<slen; i++){
 	if (cdata){
 	    if (strncmp(&str[i], "]]>", strlen("]]>")) == 0){
 		cdata = 0;
@@ -503,12 +508,15 @@ xml_chardata_cbuf_append(cbuf *cb,
     int  retval = -1;
     int  i;
     int  cdata; /* when set, skip encoding */
+    size_t len;
 
     /* The orignal of this code is in xml_chardata_encode */
     /* Step: encode and expand str --> enc */
     /* Same code again, but now actually encode into output buffer */
     cdata = 0;
-    for (i=0; i<strlen(str); i++){
+
+    len = strlen(str);
+    for (i=0; i<len; i++){
 	if (cdata){
 	    if (strncmp(&str[i], "]]>", strlen("]]>")) == 0){
 		cdata = 0;
diff --git a/lib/src/clixon_xpath.c b/lib/src/clixon_xpath.c
index 43845787..29084fb6 100644
--- a/lib/src/clixon_xpath.c
+++ b/lib/src/clixon_xpath.c
@@ -75,7 +75,6 @@
 #include <stdint.h>
 #include <syslog.h>
 #include <fcntl.h>
-#include <assert.h>
 
 /* cligen */
 #include <cligen/cligen.h>
@@ -538,6 +537,7 @@ xpath_parse(const char  *xpath,
 	clicon_log(LOG_NOTICE, "XPATH error: on line %d", xpy.xpy_linenum);
 	if (clicon_errno == 0)
 	    clicon_err(OE_XML, 0, "XPATH parser error with no error code (should not happen)");
+	xpath_scan_exit(&xpy);
 	goto done;
     }
     if (clicon_debug_get() > 1){
diff --git a/lib/src/clixon_xpath_parse.y b/lib/src/clixon_xpath_parse.y
index 825203aa..5619344a 100644
--- a/lib/src/clixon_xpath_parse.y
+++ b/lib/src/clixon_xpath_parse.y
@@ -126,6 +126,20 @@
 
 #include "clixon_xpath_parse.h"
 
+/* Best debugging is to enable PARSE_DEBUG below and add -d to the LEX compile statement in the Makefile
+ * And then run the testcase with -D 1
+ * Disable it to stop any calls to clicon_debug. Having it on by default would mean very large debug outputs.
+ */
+#if 0
+#define _PARSE_DEBUG(s) clicon_debug(1,(s))
+#define _PARSE_DEBUG1(s, s1) clicon_debug(1,(s), (s1))
+#define _PARSE_DEBUG2(s, s1, s2) clicon_debug(1,(s), (s1), (s2))
+#else
+#define _PARSE_DEBUG(s)
+#define _PARSE_DEBUG1(s, s1)
+#define _PARSE_DEBUG2(s, s1, s2)
+#endif
+
 extern int clixon_xpath_parseget_lineno  (void); /*XXX obsolete ? */
 
 /* 
@@ -366,92 +380,92 @@ xp_nodetest_function(clixon_xpath_yacc *xpy,
 /*
 */
 
-start       : expr X_EOF         { _XPY->xpy_top=$1;clicon_debug(3,"start->expr"); YYACCEPT; } 
-            | locationpath X_EOF { _XPY->xpy_top=$1;clicon_debug(3,"start->locationpath"); YYACCEPT; } 
+start       : expr X_EOF         { _XPY->xpy_top=$1;_PARSE_DEBUG("start->expr"); YYACCEPT; } 
+            | locationpath X_EOF { _XPY->xpy_top=$1;_PARSE_DEBUG("start->locationpath"); YYACCEPT; } 
             ;
 
-expr        : expr LOGOP andexpr { $$=xp_new(XP_EXP,$2,NULL,NULL,NULL,$1, $3);clicon_debug(3,"expr->expr or andexpr");  } 
-            | andexpr { $$=xp_new(XP_EXP,A_NAN,NULL,NULL,NULL,$1, NULL);clicon_debug(3,"expr-> andexpr"); } 
+expr        : expr LOGOP andexpr { $$=xp_new(XP_EXP,$2,NULL,NULL,NULL,$1, $3);_PARSE_DEBUG("expr->expr or andexpr");  } 
+            | andexpr { $$=xp_new(XP_EXP,A_NAN,NULL,NULL,NULL,$1, NULL);_XPY->xpy_top=$$;_PARSE_DEBUG("expr-> andexpr"); } 
             ;
 
-andexpr     : andexpr LOGOP relexpr { $$=xp_new(XP_AND,$2,NULL,NULL,NULL,$1, $3);clicon_debug(3,"andexpr-> andexpr and relexpr"); } 
-            | relexpr { $$=xp_new(XP_AND,A_NAN,NULL,NULL,NULL,$1, NULL);clicon_debug(3,"andexpr-> relexpr"); } 
+andexpr     : andexpr LOGOP relexpr { $$=xp_new(XP_AND,$2,NULL,NULL,NULL,$1, $3);_PARSE_DEBUG("andexpr-> andexpr and relexpr"); } 
+            | relexpr { $$=xp_new(XP_AND,A_NAN,NULL,NULL,NULL,$1, NULL);_PARSE_DEBUG("andexpr-> relexpr"); } 
             ;
 
-relexpr     : relexpr RELOP addexpr { $$=xp_new(XP_RELEX,$2,NULL,NULL,NULL,$1, $3);clicon_debug(3,"relexpr-> relexpr relop addexpr"); } 
-            | addexpr { $$=xp_new(XP_RELEX,A_NAN,NULL,NULL,NULL,$1, NULL);clicon_debug(3,"relexpr-> addexpr"); } 
+relexpr     : relexpr RELOP addexpr { $$=xp_new(XP_RELEX,$2,NULL,NULL,NULL,$1, $3);_PARSE_DEBUG("relexpr-> relexpr relop addexpr"); } 
+            | addexpr { $$=xp_new(XP_RELEX,A_NAN,NULL,NULL,NULL,$1, NULL);_PARSE_DEBUG("relexpr-> addexpr"); } 
             ;
 
-addexpr     : addexpr ADDOP unionexpr { $$=xp_new(XP_ADD,$2,NULL,NULL,NULL,$1, $3);clicon_debug(3,"addexpr-> addexpr ADDOP unionexpr"); } 
-            | unionexpr { $$=xp_new(XP_ADD,A_NAN,NULL,NULL,NULL,$1, NULL);clicon_debug(3,"addexpr-> unionexpr"); } 
+addexpr     : addexpr ADDOP unionexpr { $$=xp_new(XP_ADD,$2,NULL,NULL,NULL,$1, $3);_PARSE_DEBUG("addexpr-> addexpr ADDOP unionexpr"); } 
+            | unionexpr { $$=xp_new(XP_ADD,A_NAN,NULL,NULL,NULL,$1, NULL);_PARSE_DEBUG("addexpr-> unionexpr"); } 
             ;
 
 /* node-set */
-unionexpr   : unionexpr '|' pathexpr { $$=xp_new(XP_UNION,XO_UNION,NULL,NULL,NULL,$1, $3);clicon_debug(3,"unionexpr-> unionexpr | pathexpr"); } 
-            | pathexpr { $$=xp_new(XP_UNION,A_NAN,NULL,NULL,NULL,$1, NULL);clicon_debug(3,"unionexpr-> pathexpr"); } 
+unionexpr   : unionexpr '|' pathexpr { $$=xp_new(XP_UNION,XO_UNION,NULL,NULL,NULL,$1, $3);_PARSE_DEBUG("unionexpr-> unionexpr | pathexpr"); } 
+            | pathexpr { $$=xp_new(XP_UNION,A_NAN,NULL,NULL,NULL,$1, NULL);_PARSE_DEBUG("unionexpr-> pathexpr"); } 
             ;
 
-pathexpr    : locationpath { $$=xp_new(XP_PATHEXPR,A_NAN,NULL,NULL,NULL,$1, NULL);clicon_debug(3,"pathexpr-> locationpath"); } 
-            | filterexpr { $$=xp_new(XP_PATHEXPR,A_NAN,NULL,NULL,NULL,$1, NULL);clicon_debug(3,"pathexpr-> filterexpr"); }
-            | filterexpr '/' rellocpath { $$=xp_new(XP_PATHEXPR,A_NAN,NULL,strdup("/"),NULL,$1, $3);clicon_debug(3,"pathexpr-> filterexpr / rellocpath"); }
-            | filterexpr DOUBLESLASH rellocpath { $$=xp_new(XP_PATHEXPR,A_NAN,NULL,strdup("//"),NULL,$1, $3);clicon_debug(3,"pathexpr-> filterexpr // rellocpath"); } 
+pathexpr    : locationpath { $$=xp_new(XP_PATHEXPR,A_NAN,NULL,NULL,NULL,$1, NULL);_PARSE_DEBUG("pathexpr-> locationpath"); } 
+            | filterexpr { $$=xp_new(XP_PATHEXPR,A_NAN,NULL,NULL,NULL,$1, NULL);_PARSE_DEBUG("pathexpr-> filterexpr"); }
+            | filterexpr '/' rellocpath { $$=xp_new(XP_PATHEXPR,A_NAN,NULL,strdup("/"),NULL,$1, $3);_PARSE_DEBUG("pathexpr-> filterexpr / rellocpath"); }
+            | filterexpr DOUBLESLASH rellocpath { $$=xp_new(XP_PATHEXPR,A_NAN,NULL,strdup("//"),NULL,$1, $3);_PARSE_DEBUG("pathexpr-> filterexpr // rellocpath"); } 
             ;
 
-filterexpr  : primaryexpr { $$=xp_new(XP_FILTEREXPR,A_NAN,NULL,NULL,NULL,$1, NULL);clicon_debug(3,"filterexpr-> primaryexpr"); } 
+filterexpr  : primaryexpr { $$=xp_new(XP_FILTEREXPR,A_NAN,NULL,NULL,NULL,$1, NULL);_PARSE_DEBUG("filterexpr-> primaryexpr"); } 
             /* Filterexpr predicate */
             ;
 
 /* location path returns a node-set  */
-locationpath : rellocpath { $$=xp_new(XP_LOCPATH,A_NAN,NULL,NULL,NULL,$1, NULL); clicon_debug(3,"locationpath-> rellocpath"); } 
-            | abslocpath  { $$=xp_new(XP_LOCPATH,A_NAN,NULL,NULL,NULL,$1, NULL); clicon_debug(3,"locationpath-> abslocpath"); } 
+locationpath : rellocpath { $$=xp_new(XP_LOCPATH,A_NAN,NULL,NULL,NULL,$1, NULL); _PARSE_DEBUG("locationpath-> rellocpath"); } 
+            | abslocpath  { $$=xp_new(XP_LOCPATH,A_NAN,NULL,NULL,NULL,$1, NULL); _PARSE_DEBUG("locationpath-> abslocpath"); } 
             ;
 
-abslocpath  : '/'            { $$=xp_new(XP_ABSPATH,A_ROOT,NULL,NULL,NULL,NULL, NULL);clicon_debug(3,"abslocpath-> /"); }
-            | '/' rellocpath { $$=xp_new(XP_ABSPATH,A_ROOT,NULL,NULL,NULL,$2, NULL);clicon_debug(3,"abslocpath->/ rellocpath");}
+abslocpath  : '/'            { $$=xp_new(XP_ABSPATH,A_ROOT,NULL,NULL,NULL,NULL, NULL);_PARSE_DEBUG("abslocpath-> /"); }
+            | '/' rellocpath { $$=xp_new(XP_ABSPATH,A_ROOT,NULL,NULL,NULL,$2, NULL);_PARSE_DEBUG("abslocpath->/ rellocpath");}
             /* // is short for /descendant-or-self::node()/ */
-            | DOUBLESLASH rellocpath  {$$=xp_new(XP_ABSPATH,A_DESCENDANT_OR_SELF,NULL,NULL,NULL,$2, NULL); clicon_debug(3,"abslocpath-> // rellocpath"); } 
+            | DOUBLESLASH rellocpath  {$$=xp_new(XP_ABSPATH,A_DESCENDANT_OR_SELF,NULL,NULL,NULL,$2, NULL); _PARSE_DEBUG("abslocpath-> // rellocpath"); } 
             ;
 
-rellocpath  : step                 { $$=xp_new(XP_RELLOCPATH,A_NAN,NULL,NULL,NULL,$1, NULL); clicon_debug(3,"rellocpath-> step"); } 
-            | rellocpath '/' step  { $$=xp_new(XP_RELLOCPATH,A_NAN,NULL,NULL,NULL,$1, $3);clicon_debug(3,"rellocpath-> rellocpath / step"); } 
-            | rellocpath DOUBLESLASH step { $$=xp_new(XP_RELLOCPATH,A_DESCENDANT_OR_SELF,NULL,NULL,NULL,$1, $3); clicon_debug(3,"rellocpath-> rellocpath // step"); } 
+rellocpath  : step                 { $$=xp_new(XP_RELLOCPATH,A_NAN,NULL,NULL,NULL,$1, NULL); _PARSE_DEBUG("rellocpath-> step"); } 
+            | rellocpath '/' step  { $$=xp_new(XP_RELLOCPATH,A_NAN,NULL,NULL,NULL,$1, $3);_PARSE_DEBUG("rellocpath-> rellocpath / step"); } 
+            | rellocpath DOUBLESLASH step { $$=xp_new(XP_RELLOCPATH,A_DESCENDANT_OR_SELF,NULL,NULL,NULL,$1, $3); _PARSE_DEBUG("rellocpath-> rellocpath // step"); } 
             ;
 
-step        : axisspec nodetest predicates {$$=xp_new(XP_STEP,$1,NULL, NULL, NULL, $2, $3);clicon_debug(3,"step->axisspec(%d) nodetest", $1); }
-            | '.' predicates              { $$=xp_new(XP_STEP,A_SELF, NULL,NULL, NULL, NULL, $2); clicon_debug(3,"step-> ."); } 
-            | DOUBLEDOT predicates        { $$=xp_new(XP_STEP, A_PARENT, NULL,NULL, NULL, NULL, $2); clicon_debug(3,"step-> .."); } 
+step        : axisspec nodetest predicates {$$=xp_new(XP_STEP,$1,NULL, NULL, NULL, $2, $3);_PARSE_DEBUG1("step->axisspec(%d) nodetest", $1); }
+            | '.' predicates              { $$=xp_new(XP_STEP,A_SELF, NULL,NULL, NULL, NULL, $2); _PARSE_DEBUG("step-> ."); } 
+            | DOUBLEDOT predicates        { $$=xp_new(XP_STEP, A_PARENT, NULL,NULL, NULL, NULL, $2); _PARSE_DEBUG("step-> .."); } 
             ;
 
-axisspec    : AXISNAME { clicon_debug(3,"axisspec-> AXISNAME(%d) ::", $1); $$=$1;}
-            | '@'      { $$=A_ATTRIBUTE; clicon_debug(3,"axisspec-> @"); } 
-            |          { clicon_debug(3,"axisspec-> "); $$=A_CHILD;} 
+axisspec    : AXISNAME { _PARSE_DEBUG1("axisspec-> AXISNAME(%d) ::", $1); $$=$1;}
+            | '@'      { $$=A_ATTRIBUTE; _PARSE_DEBUG("axisspec-> @"); } 
+            |          { _PARSE_DEBUG("axisspec-> "); $$=A_CHILD;} 
            ;
 
-nodetest    : '*'              { $$=xp_new(XP_NODE,A_NAN,NULL, NULL, NULL, NULL, NULL); clicon_debug(3,"nodetest-> *"); } 
-            | NAME             { $$=xp_new(XP_NODE,A_NAN,NULL, NULL, $1, NULL, NULL); clicon_debug(3,"nodetest-> name(%s)",$1); } 
-            | NAME ':' NAME    { $$=xp_new(XP_NODE,A_NAN,NULL, $1, $3, NULL, NULL);clicon_debug(3,"nodetest-> name(%s) : name(%s)", $1, $3); } 
-            | NAME ':' '*'     { $$=xp_new(XP_NODE,A_NAN,NULL, $1, NULL, NULL, NULL);clicon_debug(3,"nodetest-> name(%s) : *", $1); } 
-            | FUNCTIONNAME ')' { if (($$ = xp_nodetest_function(_XPY, $1, NULL)) == NULL) YYERROR;; clicon_debug(3,"nodetest-> nodetype():%s", $1); } 
+nodetest    : '*'              { $$=xp_new(XP_NODE,A_NAN,NULL, NULL, NULL, NULL, NULL); _PARSE_DEBUG("nodetest-> *"); } 
+            | NAME             { $$=xp_new(XP_NODE,A_NAN,NULL, NULL, $1, NULL, NULL); _PARSE_DEBUG1("nodetest-> name(%s)",$1); } 
+            | NAME ':' NAME    { $$=xp_new(XP_NODE,A_NAN,NULL, $1, $3, NULL, NULL);_PARSE_DEBUG2("nodetest-> name(%s) : name(%s)", $1, $3); } 
+            | NAME ':' '*'     { $$=xp_new(XP_NODE,A_NAN,NULL, $1, NULL, NULL, NULL);_PARSE_DEBUG1("nodetest-> name(%s) : *", $1); } 
+            | FUNCTIONNAME ')' { if (($$ = xp_nodetest_function(_XPY, $1, NULL)) == NULL) YYERROR;; _PARSE_DEBUG1("nodetest-> nodetype():%s", $1); } 
             ;
 
 /* evaluates to boolean */
-predicates  : predicates '[' expr ']' { $$=xp_new(XP_PRED,A_NAN,NULL, NULL, NULL, $1, $3); clicon_debug(3,"predicates-> [ expr ]"); } 
-            |                         { $$=xp_new(XP_PRED,A_NAN,NULL, NULL, NULL, NULL, NULL); clicon_debug(3,"predicates->"); } 
+predicates  : predicates '[' expr ']' { $$=xp_new(XP_PRED,A_NAN,NULL, NULL, NULL, $1, $3); _PARSE_DEBUG("predicates-> [ expr ]"); } 
+            |                         { $$=xp_new(XP_PRED,A_NAN,NULL, NULL, NULL, NULL, NULL); _PARSE_DEBUG("predicates->"); } 
             ;
-primaryexpr : '(' expr ')'         { $$=xp_new(XP_PRI0,A_NAN,NULL, NULL, NULL, $2, NULL); clicon_debug(3,"primaryexpr-> ( expr )"); } 
-            | NUMBER               { $$=xp_new(XP_PRIME_NR,A_NAN, $1, NULL, NULL, NULL, NULL);clicon_debug(3,"primaryexpr-> NUMBER(%s)", $1); /*XXX*/} 
-            | QUOTE string QUOTE   { $$=xp_new(XP_PRIME_STR,A_NAN,NULL, $2, NULL, NULL, NULL);clicon_debug(3,"primaryexpr-> \" string \""); }
-            | QUOTE QUOTE          { $$=xp_new(XP_PRIME_STR,A_NAN,NULL,  strdup(""), NULL, NULL, NULL);clicon_debug(3,"primaryexpr-> \" \""); } 
-            | APOST string APOST   { $$=xp_new(XP_PRIME_STR,A_NAN,NULL, $2, NULL, NULL, NULL);clicon_debug(3,"primaryexpr-> ' string '"); }
-            | APOST APOST          { $$=xp_new(XP_PRIME_STR,A_NAN,NULL, strdup(""), NULL, NULL, NULL);clicon_debug(3,"primaryexpr-> ' '"); } 
-            | FUNCTIONNAME ')'      { if (($$ = xp_primary_function(_XPY, $1, NULL)) == NULL) YYERROR; clicon_debug(3,"primaryexpr-> functionname ()"); }
-            | FUNCTIONNAME args ')' { if (($$ = xp_primary_function(_XPY, $1, $2)) == NULL) YYERROR;  clicon_debug(3,"primaryexpr-> functionname (arguments)"); } 
+primaryexpr : '(' expr ')'         { $$=xp_new(XP_PRI0,A_NAN,NULL, NULL, NULL, $2, NULL); _PARSE_DEBUG("primaryexpr-> ( expr )"); } 
+            | NUMBER               { $$=xp_new(XP_PRIME_NR,A_NAN, $1, NULL, NULL, NULL, NULL);_PARSE_DEBUG1("primaryexpr-> NUMBER(%s)", $1); /*XXX*/} 
+            | QUOTE string QUOTE   { $$=xp_new(XP_PRIME_STR,A_NAN,NULL, $2, NULL, NULL, NULL);_PARSE_DEBUG("primaryexpr-> \" string \""); }
+            | QUOTE QUOTE          { $$=xp_new(XP_PRIME_STR,A_NAN,NULL,  strdup(""), NULL, NULL, NULL);_PARSE_DEBUG("primaryexpr-> \" \""); } 
+            | APOST string APOST   { $$=xp_new(XP_PRIME_STR,A_NAN,NULL, $2, NULL, NULL, NULL);_PARSE_DEBUG("primaryexpr-> ' string '"); }
+            | APOST APOST          { $$=xp_new(XP_PRIME_STR,A_NAN,NULL, strdup(""), NULL, NULL, NULL);_PARSE_DEBUG("primaryexpr-> ' '"); } 
+            | FUNCTIONNAME ')'      { if (($$ = xp_primary_function(_XPY, $1, NULL)) == NULL) YYERROR; _PARSE_DEBUG("primaryexpr-> functionname ()"); }
+            | FUNCTIONNAME args ')' { if (($$ = xp_primary_function(_XPY, $1, $2)) == NULL) YYERROR;  _PARSE_DEBUG("primaryexpr-> functionname (arguments)"); } 
             ;
 
 args        : args ',' expr { $$=xp_new(XP_EXP,A_NAN,NULL,NULL,NULL,$1, $3);
-                              clicon_debug(3,"args -> args expr");}
+                              _PARSE_DEBUG("args -> args expr");}
             | expr          { $$=xp_new(XP_EXP,A_NAN,NULL,NULL,NULL,$1, NULL);
-                              clicon_debug(3,"args -> expr "); }
+                              _PARSE_DEBUG("args -> expr "); }
 	    ;
 
 string      : string CHARS  { 
@@ -459,9 +473,9 @@ string      : string CHARS  {
 			 $$ = realloc($1, len+strlen($2) + 1); 
 			 sprintf($$+len, "%s", $2); 
 			 free($2);
-			 clicon_debug(3,"string-> string CHAR");
+			 _PARSE_DEBUG("string-> string CHAR");
                }
-            | CHARS         { clicon_debug(3,"string-> "); } 
+            | CHARS         { _PARSE_DEBUG("string-> "); } 
             ;
 
 
diff --git a/test/test_perf_json.sh b/test/test_perf_json.sh
new file mode 100755
index 00000000..3dfab307
--- /dev/null
+++ b/test/test_perf_json.sh
@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+# JSON performance test:
+# 1. parse a long string
+
+# Magic line must be first in script (see README.md)
+s="$_" ; . ./lib.sh || if [ "$s" = $0 ]; then exit 0; else return 0; fi
+
+: ${clixon_util_json:="clixon_util_json"}
+
+# Number of list/leaf-list entries in file
+: ${perfnr:=20000}
+
+fjson=$dir/long.json
+
+new "generate long file $fjson"
+echo -n '{"foo": "' > $fjson
+for (( i=0; i<$perfnr; i++ )); do  
+    echo -n "a" >> $fjson
+done
+echo '"}' >> $fjson
+echo "$fjson"
+
+new "json parse long string"
+expecteof_file "time -p $clixon_util_json" 0 "$fjson" 2>&1 | awk '/real/ {print $2}'
+
+rm -rf $dir
+
+# unset conditional parameters 
+unset clixon_util_xml
+unset perfnr
+
+new "endtest"
+endtest