Performance for this kind of particle effect will be even better once Webgl2 is widely available. Transform feedback (or other hacks) let you manipulate the particle positions on the videocard itself. There's a great article about them here: http://prideout.net/blog/?p=67
Done! Well, I hope it's done - I haven't made a chrome extension before. Let me know if it breaks...
https://github.com/Ilink/tabIndent.js
Cloned the project, should be available in the "extension/chrome" directory.