Have you set the test build settings for quality for the highest or lowest? Try the lowest quality and see if that helps you play through your test levels. I have only tested 8800 Nvidia cards and have had great success so far.
"TGC Tested Cards At 01/11/07:
* GeForce 8800 GTX - ForceWare 163
- 100% compatible and recommended
* GeForce 8500 GT - ForceWare 163
- average performance with most effects switched off
- slow with all effects switched on (not recommended)
* ATI Radeon 2900 XT - Catalyst 7.8 & 7.9
- known issue : test game runs, but screen can switch to black
- known issue : random freezing - hard lock in driver
* ATI Radeon 2900 XT - Catalyst 7.7
- known issue : under powered in performance and odd 3D overloads
- known issue : mipmapping corruption, no freezing or hard lock
USER Tested Cards:
* 8800 GTS 640mb - Works great
* 8800 GTS 320mb - ForceWare 163 - All ran very smoothly
Untested Cards:
* GeForce 8800 Ultra
* GeForce 8800 GT
* GeForce 8600 GTS
* GeForce 8600 GT
* GeForce 8400 GS
Minimum Specification FAQ:
Q> I have a minimum specification machine and want to run X10 as fast as possible, how can I do this?
A> There are a number of measures you can take to ensure you get the fastest performance. The first major change should be to switch off all refraction effects in the level, by going to the X10 effects menu and moving the slider bar to zero for window and water refraction. You can also switch off reflection, shadows and bloom in the same way to increase performance. You can also reduce the windows desktop size so that when the X10 engine runs, it uses a smaller display resolution. The smaller the resolution, the less work the pixel shaders have to do and the faster your game level will be. You can also watch the resource meter to see what happens during your level, and respond with the correct level optimization based on which resource maxes out. See the user manual for advice on how to do this.
LeeBamber"