Right now I'm using the latest version of IE7 to browse the forums which it does adequately, albeit more slowly than any other sites. When using my normal browser, Opera 9.26, the forums sometimes just won't load, as was the case for me five minutes ago. This is a problem that repeatedly occurs, normally during this period of the day.I've talked to several other players on ICO who have reported similar issues.
firefox.
I've got the latest versions of Safari, IE, Firefox, and Opera installed (and the stable versions of Firefox and Opera). I think I might even have Flock. So call it an informed choice (Firefox 3 looks promising though).
With regards to the forums, like Fumikaa, I've found them to have speed up considerably lately, although to counter that, I've been plauged by several bugs lately. Where's IP.Board, Burning Board or phpBB when you need them?