That site's data is inaccurate at best - it uses its own server logs to compile that data rather than aggregating the data from across the Web as thecounter.com does. Besides, from a development standpoint, it's best to focus on all four major rendering engines anyway: Trident (IE 6/7/soon to be 8), Gecko (Firefox, Flock, DocZilla, Epiphany, Galeon, Iceweasel, et al.), Presto (Opera), KHTML/WebKit (Konqueror/Safari respectively; I also believe OmniWeb uses WebKit as well, could be wrong though). (Yes, I know IE 5.x uses the Trident engine as well, but that's beside the point. It's an antique anyway, can't run natively on XP or Vista, and anyone using a version of Windows that can handle it will likely be running IE 6 or a real browser anyway.)
It seems to be mozzila is very faster at first time when you open a new page and it seems to IE is very slower at first time when you open a new page... But after that if those web pages are having so many images, means web page is having high amount of data, than Mozzila some times not responding to that, well i have not yet found this kind of problem with IE 8... My vote for IE...
Ignorance can only get a person so far. Why don't you give it a try instead and see for yourself how it is? Remember, right now it's a beta (meant for developers), so don't test your own sites against it. Test standards-compliant sites like green-beast.com alistapart.com and accessify.com against it, then report any bugs or other problems you find to the IE development team.
I'm having a play around with several. Using Safari at the moment,it's certainly a lot "cleaner" than IE,with everything somehow fitting in better. For me though, IE suits my needs fine, it is still the market leader, and while ever this is the case, developers will build to meet the needs of the market. I think i will give IE8 a try soon.