[ubuntu] Sluggish graphics with ATI HD 3300

I have a Biostar 790GX 128mb motherboard, which comes with an integrated HD 3300 graphics core. According to many benchmarks, the graphics performance of the integrated core is comparable to many existing graphics cards.

Karmic recognizes and utilizes the device without a problem. Compiz works in extra effects mode. However, the whole desktop is sluggish. glxgears cannot do more than 200 fps. Screensavers (some of them) are extremely choppy.

I tried installing the latest fglrx from the ATI website, but it didn't really help.

This was an upgrade from 9.04. Would it help performance-wise, if I were to install from scratch? This sluggish desktop is really killing me.