> Now the problem is that Google web apps are tuned for Chrome, so users will complain their gmail is slow on FF.

I've heard this argument often, but it does not really resonate with me well. I've always used Gmail in Firefox and never noticed it being especially slow. I just tried it now and emails open seemingly instantly when I click on them. It feels quicker than ~100ms on average and certainly not slower than 200ms even for the occasional large email or hiccup. I just don't see how this can be used as a reasonable metric for choosing a browser.