Hi Marcel,

> I haven't tried it in practice, but Apple says their 
> rectangular-texture extensions can be used for rotated images etc.  
> They had a rather impressive demo of a 50+ MB bitmap being rotated at 
> something like 20-30 frames/sec on ADC-TV.

Okay, in this case here is what you *really* want to do (given
everything works as the spec says it should ;-) 
* Make an AGP texture for Squeak's display
* Use "render to texture" for your cached morphs
* Update the screen from the display texture

Why do it that way?! You are still able to read the display bits back in
if needed [*] but for the default case (where this isn't needed) you'll
go as fast as the hardware permits (using textures for backing morphs,
HW blits to the "Display" and HW blits for "ioShowDisplay" and friends).
I can't think of anything that would be faster and provide _exactly_ the
same semantics we have in Squeak today

[*] Unfortunately, I'm expecting that render to texture will not work
correctly in the case that you provide an AGP texture and expect the
data to be up-to-date after the blit completed. But who knows...

Cheers,
  - Andreas