I used vimperator and experienced crazy slowdown on Firefox in both OSX and Ubuntu. This happens after you browse for a while. Wasn't sure why initially. Things

I used vimperator and experienced crazy slowdown on Firefox in both OSX and Ubuntu. This happens after you browse for a while. Wasn't sure why initially. Things improved dramatically after reinstalling the addon. But I had to do it frequently so it wasn't worth it. I think it's because things are saved in history for a long time or history chain of sites in a tab is very long. Edit: Only extension that is vim-like that hasn't let me down is cvim for chromium/chrome.