I use firefox on kubuntu, and while it's laggy sometimes, I don't think it's any worse than other players' experiences (judging by the comments here). I haven't made any optimisations specifically for this site.

I suspect that most of the time it's either a server-side issue or an internet connection problem.

Are you saying it's something to do with the OS or the browser? And what makes you say that - have you performed any comparable tests (e.g. different OS same browser, same OS different browser)?

cant play aswell on linux. same problem for me. unluckely i have to play it on windows ip.

Are you using firefox or IE on windoze? Have you tried browsers other than firefox on linux - konqueror, opera, IE under wine etc?

i dual boot windows and linux. I use firefox in both. in windows (xp), its much much more responsive

by "lag", i mostly mean input lag, and sounds. hitting buttons, and hearing sounds are delayed. sometimes sounds are skipped. Its playable in ubuntu, but MUCH more faster and comfortable in windows.

Right, I see what you mean now.

This might be due to the fact that Firefox for Windows is built with PGO (Profile Guided Optimisation) but your Linux distro (Ubuntu) don't do that with their build (and neither do Mozilla with their Linux build).

You can try running a Windows Firefox build under wine in Linux. If it's faster than in native Linux then PGO is probably the issue. This is not really an OS issue, more like a Firefox one (the build config) and also a compiler issue.

running on linux too, no problems here whatsoever. using debian lenny + iceweasel (= firefox)

I run IE and Vista. I often see that over time more and more of my RAM is being used until IE grinds to a halt. This is with no other user apps running.

Yeah I assume its a Firefox issue with ubuntu, because there are already bug reports with flash or video sites in ubuntu. I have wine but I haven't played around with it yet.

much more responsive in Wine. although the chip sounds are different/weird, but that's not a problem

Well then, maybe you can vote for the PGO bug over at Launchpad or something...