Hi George,
many thanks for your hint. I will try to rebuild the level. The two versions indeed run fine with a proper 3D chip. I should have rendered this more clearly in my post.
I just couldn't figure out why your A6 version runs fine even on a GM chip and the A7 version is so slow. It would be very interesting to know what I had to consider when trying to build a game that runs even on low end hardware (besides the hints in the manual).
Thanks a lot for your help (ans of course thanks for the great AUM magazine)
Stefan