I'm trying Firefox about once a year because I want to like it for being independent and privacy minded. But every time I find myself going back to other browsers for seemingly minor reasons.

The most important one is that firefox opens new windows a few hundered milliseconds too slowly (on Mac OS X). Just a little bit too slowly for me to just hit Cmd+N and blindly start typing a url. I have to stop and pay attention to when the window is ready, hundereds of times a day.

Another annoyance, a much less important one, is that Firefox wastes a lot of screen real estate at the top.