This has already been answered in another topic:
Press Q to change the quality, which allows the game to run faster.
If it's still slow, try closing other windows.
If that doesn't work, try pressing Ctrl + Alt + Del, click the tab labelled Processes, and find your internet browser. Right click it, and set the Priority to High. I'm not sure how this works on Vista or Windows 7, but this is how it works for XP.
I HELP MAKE SNBM... HONEST!