Quote from Lateralus :

It was indeed my drivers. Before when alone I started at 43 FPS, now I get 95. With 10 AI cars I got 9-16 FPS at the race start, now I get 45-50. An enormous difference.

Thanks a lot for the help everyone, and especially DEVIL 007 for reminding me about the possible driver issue.

P.S. As a small side question in order to avoid creating a new thread, what does the "Simple Track" option do? I have it set to "Off" currently. When I try either of the other settings, it absolutely murders my framerate. Last time I tried it my FPS went from 60+ to 5.

I am glad it worked.
There is really something wrong with ATI drivers for LFS.Maybe they dropping more and more optimization support in their drivers for DX8.Dunno what is exactly the issue.Maybe the 6.5 works fine.

Quote from Lateralus :

It was indeed my drivers. Before when alone I started at 43 FPS, now I get 95. With 10 AI cars I got 9-16 FPS at the race start, now I get 45-50. An enormous difference.

I have had similar results.

I have an ATI 9800 Pro and was getting frame rates in the low 40s when using the Catalyst 6.6 drivers. I downgraded to the 5.11 drivers and my frame rates shot up into the 90s (with HVS enabled, see below).

Furthermore, HVS now works properly for me. Enabling HVS used to reduce my frame rates with the 6.6 drivers, but with the 5.11 drivers enabling HVS increased my frame rates from the 50s to the 90s.

Given that the old ATI drivers provide better performance than the new ones, can we expect future drivers from ATI to fix up the problem that slows LFS down in systems running driver versions newer than 5.11?

Quote from Peptis :

Given that the old ATI drivers provide better performance than the new ones, can we expect future drivers from ATI to fix up the problem that slows LFS down in systems running driver versions newer than 5.11?

Hi Peptis,
sorry to say that but unfortunately not.It is known with NVIDIA and ATI as well they usually discontinue full support for older hardware after some time in their drivers.It mean they dont fix the drivers performance for some older hardware.

Another things that they make optimization for drivers to get more peformance in DX9 titles rather then DX8 which use LFS.

Also LFS is small game to get some focus from ATI