diff --git a/CHANGELOG b/CHANGELOG
index 3ed6d02..1970358 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Avoid the try..catch block in Ajax.Response#_getResponseJSON unless required. [Tobie Langel]
+
 * Add more tests to Element.update. Closes #9327. [Tobie Langel]
 
 * Make the Ajax.Response#headerJSON property correctly decode unicode characters. Closes #9285. [Marius Feraru, Tobie Langel]
diff --git a/src/ajax.js b/src/ajax.js
index bea5d9a..7f5c701 100644
--- a/src/ajax.js
+++ b/src/ajax.js
@@ -287,11 +287,11 @@ Ajax.Response = Class.create({
   
   _getResponseJSON: function() {
     var options = this.request.options;
+    if (!options.evalJSON || (options.evalJSON != 'force' && 
+      !(this.getHeader('Content-type') || '').include('application/json')))
+        return null;
     try {
-      if (options.evalJSON == 'force' || (options.evalJSON &&
-          (this.getHeader('Content-type') || '').include('application/json')))
-        return this.transport.responseText.evalJSON(options.sanitizeJSON);
-      return null;
+      return this.transport.responseText.evalJSON(options.sanitizeJSON);
     } catch (e) {
       this.request.dispatchException(e);
     }