I'm running patch U on a Dell 600m laptop. I've attached the dxdiag output. Basically, I'm running the default LFS config and the following hardware/software:

Phoenix ROM BIOS PLUS Version 1.10 A17
1280MB RAM
DirectX 9.0c (4.09.0000.0904)
Intel(R) Pentium(R) M processor 2.00GHz
MOBILITY RADEON 9000 64 mb @ 1400 x 1050 (32 bit) (60Hz)
ati2dvag.dll 6.14.0010.6587 (English)

The problem that I'm having is that the game runs fine for about 5 minutes, then CPU utilization hits 100% and the game gets choppy and intermittently responsive. I can exit the game gracefully and relaunch lfs.exe only to again have about 5 minutes of play before it gets choppy again. I had the same problem with a prior patch as well (P). I'm gonna try rolling back to older versions to see if I still have the same problem, but I thought I'd ask in case anybody else has seen this.

Sounds like somethings overheating to me. Make sure your laptops in a solid base where air can easily enter the vents.

The CPU is very probably downstepping itself because of overheating. Time to disassemble the laptop and get that ton of dust out of there...

Looks like you guys were right. I disabled speedstep and could go a full race but at <30 fps. Then I re-enabled speedstep, elevated the laptop and placed a room fan next to it and was back at >45 fps and a full race. Thanks.