Unfortunately I don't have any inspiring ideas, just some standard ones that I can suggest.
A) Make sure you haven't set the battery settings to low. I know on my lap top if I have it set to the power-saving setting than everything runs pretty poorly.
B) Update video card drivers. Usually my first suggestion for anything video related. Or, if you just updated them, roll back to an older version.
C) Make sure you don't have a lot of stuff running in the back ground. Did you download something recentley and then this started happening? Make sure it isn't doing funny stuff in the back ground.
That's all I can think of off the top of my head. Like I said, it's nothing unorthodox, really, but hopefully it might help.