diff --git a/lib/attribute.js b/lib/attribute.js
index 0d1668d..32f67c8 100644
--- a/lib/attribute.js
+++ b/lib/attribute.js
@@ -182,10 +182,20 @@ Attribute.prototype.toString = function () {
   return JSON.stringify(this.json);
 };
 
+// The array contains placeholders for digits in the format.
+// Storing search stings in the array makes the search much faster than using regular expressions.
+var FORMAT_SEARCH_STRING = [];
+function getFormatSearchString(index) {
+	if (!FORMAT_SEARCH_STRING[index]) {
+		FORMAT_SEARCH_STRING[index] = '{' + index + '}';
+	}
+	return FORMAT_SEARCH_STRING[index];
+}
+
 function formatGuid(format, data) {
   for (var i = 0; i < data.length; i++) {
-    var re = new RegExp('\\{' + i + '\\}', 'g');
-    // Leading 0 is needed if value of data[i] is less than 16 (of 10 as hex). 
+    var re = getFormatSearchString(i);
+    // Leading 0 is needed if value of data[i] is less than 16 (of 10 as hex).
     var dataStr = data[i].toString(16);
     format = format.replace(re, data[i] >= 16 ? dataStr : '0' + dataStr);
   }