Macbook Pro Screen update issues

My wife has this great Macbook Pro 15", and I "don't mind" using it every now and then. I noticed that when running on batteries, screen updates are a bit strange:

  * When scrolling down a webpage, the page get garbled. Scrolling the garbled piece out of the window and in again sometimes fixes it.
  * When resizing a Finder window, the icons in the window flicker a lot, you can see them being cleared and redrawn.

I noticed more people having these problems on several forums, and I also read that resetting the PRAM could fix it. Well, I just reset the PRAM and it seems to have fixed it, indeed.

I used the method mentioned on Apple's support page, which tells you to shut the computer down, and boot it up holding the command, option, P and R keys. As soon as you see it shutting down after you've started it up, release the keys.

This is all I did, and it seems to have fixed it.