Tried searching for this similiar issue, found some close ones but not quite.

When scrolling thru a webpage (either opera or firefox) its pretty choppy and causes whatever song im listening to, to skip.
The strange thing is that i can put all the 3d settings on, and spin my workspace around with no problems, and no choppyness and no skips in a song. I've tried turning compiz off with no changes. This leads me to believe theres a 2d issue, as 3d runs flawlessly.

Running Heron, the restricted ATIs, and compiz. Any ideas? Sorry if this is somewhere else, i looked.