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I've been running timedemos with Portal on Steam beta.

Anything higher than 1440x900on the MacBook Pro Core i5 with 256M VRAM and the avg FPS drop to unplayable (10-12 fps). That's at "recommended" medium quality settings.

The MacBook Pro Core i7 with 512M VRAM kept cranking along at 30+ FPS even at 1920x1200, max settings, 4X multisampling, and 8X Aniso.
 
I've been running timedemos with Portal on Steam beta.

Anything higher than 1440x900on the MacBook Pro Core i5 with 256M VRAM and the avg FPS drop to unplayable (10-12 fps). That's at "recommended" medium quality settings.

The MacBook Pro Core i7 with 512M VRAM kept cranking along at 30+ FPS even at 1920x1200, max settings, 4X multisampling, and 8X Aniso.

That's quite telling.

Are you going to revise your original conclusion about 256 vs 512? It seems that large a difference is probably not due to the relatively smaller increase in CPU speed between the i5 and i7...
 
Supper supper interested in how the source engine mac games will run.
256 should be good for most of the older ones, but L4D might push things a little
 
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