I tried to do this, and I had to switch back. My setup is that I have loads of tabs open, with a vertical tab manager on the side. And FF has a pretty nice extension for that, plus you can take back some screen space by removing the top tabs using some css.

Anyway, when I have the same tabs and extensions in FF as in Chrome, the FF CPU usage is huge. I tried several things from the web, but nothing helped. Now I'm back on Chrome, which is less nice looking and less convenient, but the CPU usage is barely anything.