updated for version 7.3.1149
Problem:    New regexp engine: Matching plain text could be faster.
Solution:   Detect a plain text match and handle it specifically.  Add
            vim_regfree().
diff --git a/src/fileio.c b/src/fileio.c
index b93ae1b..f1db983 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -7921,7 +7921,7 @@
 	    if (ap->pat == NULL)
 	    {
 		*prev_ap = ap->next;
-		vim_free(ap->reg_prog);
+		vim_regfree(ap->reg_prog);
 		vim_free(ap);
 	    }
 	    else
@@ -10070,7 +10070,7 @@
 	result = TRUE;
 
     if (prog == NULL)
-	vim_free(regmatch.regprog);
+	vim_regfree(regmatch.regprog);
     return result;
 }
 #endif