Try Chrome beta, it's the best browser. AS for the stock browser, try to clear data and clear cache from the app manager window.
I was about to say the same thing about clearing cache/data. Also, I tried Chrome, but it had some issues on some pages that cause it to lock up. I'll try it again later, but I'm extremely happy with Samsung's updated browser. Like Chrome, it syncs with your Google account, so I get my bookmarks shared across platforms (although I don't think it opens active windows like Chrome does). They even finally added an exit button, sort of. Just go to tabs/pages and close the last one, and it will close the browser.
However, I do have some issues with the stock browser. First, no home button. Second, they still have a separate brightness control, which is beyond stupid. At least give us the option to lock it to system brightness!