json-lex-string-lookahead-speed.diff

diff --git i/src/common/jsonapi.c w/src/common/jsonapi.c
index 98e4ef09426..63d92c66aec 100644
--- i/src/common/jsonapi.c
+++ w/src/common/jsonapi.c
@@ -858,10 +858,25 @@ json_lex_string(JsonLexContext *lex)
 		}
 		else if (lex->strval != NULL)
 		{
+			size_t chunklen = 1;
+
 			if (hi_surrogate != -1)
 				return JSON_UNICODE_LOW_SURROGATE;
 
-			appendStringInfoChar(lex->strval, *s);
+			while (len + chunklen < lex->input_length)
+			{
+				char next = *(s + chunklen);
+
+				if (next == '\\' || next == '"' || (unsigned char) next < 32)
+					break;
+
+				chunklen++;
+			}
+
+			appendBinaryStringInfo(lex->strval, s, chunklen);
+
+			s += (chunklen - 1);
+			len += (chunklen - 1);
 		}
 	}