switching off desktop composition did it... I don't believe it
I mean yes, obviously desktop composition is supposed to take load off the CPU and let the GPU handle it, but surely not at the significant expense of GPU performance...
The GPU isn't being pushed to full speed during Flash games or anything 2D as far as I can see. I don't know how to get it to run at full speed just to see what might happen to Flash performance. These games barely register on the activity indicator in the catalyst control centre. Occasionally 1%, a jump to 6% once or twice, generally zero.
I've played around with the advanced eye candy settings, trying with desktop composition but without translucency etc, but the only one that seems to have any noticeable difference to Flash game performance is desktop composition. Win7 aero looks awful without translucency IMO, so I'm trying the Windows classic theme for a while. I've yet to figure out how to get traditional right-click menus back on taskbar buttons, rather than the jump list style. I might just disable desktop composition when I want to play Flash games, but then I get the feeling that overall system performance has got to be affected if a simple Flash game is. Having said that, Flash isn't known for its system resource efficiency.