I've used the vimium for chrome, vimfx for firefox and they both have similar problems:
1) Impossible to navigate some sites 2) Slows down the browser to a crawl over time
Generally, not a usable long-term solution
1) Impossible to navigate some sites 2) Slows down the browser to a crawl over time
Generally, not a usable long-term solution
It's true that some sites are harder to navigate, though.
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.