I would suggest you use Chrome, Firefox, Safari, or Opera. Probably in that order. Don't even bother with Internet Explorer.
Comparing the newest versions of all browsers, their JavaScript speed is:
Safari 4 > Chrome 2 > Opera 10 > Firefox 3.5 > IE 8.
Although Opera 10 runs 50% slower than Firefox 3.5 on AMD Phenoms for some reason.
To put it in perspective: Firefox 3.5 is 250% faster than IE8. Chrome and Safari are about 400% faster than IE8. IE8 is only marginally faster than IE7. It's pathetic.