Page Speed is a family of tools for optimizing the performance of web pages.
The Page Speed browser extensions, available for Chrome and Firefox, allow you to evaluate the performance of your web pages and to get suggestions on how to improve them.
Page Speed Tool Download

Yesterday I found a bug in FCK editor every time when I was clicking on source code it was adding this weird script

in text panel.

I just struggled a lot to find solution and just though to share with all of you guys.

Problem caused by firefox add-on “browser highlighter”. So just remove “browser highlighter” add-on from your firefox and its done!

I hope you know how to remove add-on from firefox!