[danieldon]

My experience on OS X:

First, Firefox takes a long time to start up, probably between 5 and 10 seconds. Tabs open and close quickly, but there's a constantly noticable 1/2-1 second delay when opening a new window. ⌘-N ... short pause ... window opens. With both Chrome and Safari it's instantaneous.

But perhaps most importantly, Chrome runs everything in separate processes and when you close a tab, that memory is freed up. This is a huge deal compared to both Firefox and Safari. It means you can just leave Chrome open forever, whereas Firefox and Safari will just gradually eat up more and more RAM. If RAM usage from other processes pushes Firefox's memory to disk, then it's even worse, since you then need to wait forever to do anything with the browser while it pulls it from disk. Safari is similar, but not as bad since it's more responsive overall. While with Chrome all you'd need to do is close a couple tabs, with Firefox you have restart the whole app.

And I experience all of this on a Firefox accounts with zero extensions.

There really is no contest. If you aren't seeing a difference I can only presume it's because of your usage patterns or possibly the platform, although I'm skeptical of the latter since people widely report Firefox hogging memory on every platform.