Illustrator CS 4 Slow Toolbar Redraw - Windows 7 64bit

So I've been using Adobe Illustrator CS4 for a while. On my work PC it runs fine (Vista, go figure), but at home on my beastly Windows 7 box (ATI Radeon 4870), it would refresh REALLY slowly.

So ignoring all the suggestions of updating drivers, I set about trying to fix it. Reset the prefs, deleted the temp files etc... to no avail.

Then I went and updated the ATI driver. And lo-and-behold, it fixed it.