Game problems through BootCamp Macbook Pro

I have always had a lot of problems when playing games through bootcamp. Especially with Call of Duty 4. It freezes up constantly in the menus and just has lots of problems. Some games wont run at all in bootcamp, but the odd thing is that all these problems don't ever occur when I open the games in Parallels. Granted frame rates are a lot lower of course, but the games function fine.

I also noticed when playing Modern Warfare 2 today with my friend, my macbook pro blows his HP out of the water when comparing the in-game Frame rates and graphics, but his menus and loading screens go sooo much faster.

Is there anything I can do to solve these problems?
Thanks very much to anyone who can help.

Macbook Pro 2.4GHz (2010), 4GB RAM