I first picked up FireFox about 18 months or so ago - mainly because the previous owner of my IBM Thinkpad had an early (v0.7 I think) release installed. I liked the minimalist UI and tabbed browsing so I've stuck with it since then.
Over the last few releases (forget where I am now - 1.5.2?) it seems to have got progressively slower and slower. Starting the thing up got slower - I'm not the type to leave it permanently open (despite what my GameDev posting statistics might suggest) so this annoyed me. Then on one of the previous releases I started getting odd little stalls from the UI - It'd start loading something in one tab and it'd lock the whole browser. Earlier builds just locked up the single tab until it'd done whatever it was doing...
FireFox is now getting in my way. I want my computer to bend towards the way I work, not the other way around. As soon as any software crosses that line AND I have a free alternative its just gotta go.
Since late '05 I've also been running IE7 Beta-1. Saw it when I was over in Seattle and thought I'd give it a whirl. Had quite a few bugs in it and I didn't much like the interface. The rest of it seemed pretty much like IE6 with tabbed browsing.
This evening I decided to go check out IE Beta-2. It's been out for a while, but I've been too busy and had little motivation to bother upgrading.
It's MUCH better than beta-1 from first impressions. It's faster, it's not stalled. It's got the Vista-like UI as well now (much less chunky than beta-1). I like it.
So, I went into the "Set Program Access and Defaults" and changed back to IE. Bye-bye FireFox - you were good, but now your old fat and slow [lol]
During the uninstall of Beta-1 I somehow managed to break Media Player. So I've also got the MP11 beta to play with now.