Well lap time increase is natural, since the game is slower
But yeah if it affects the possibility of finishing a lap then it's problematic.
The bumps in the road on The Last Race are near the end of the lap. The first 3/4 is extremely smooth (minus a specific jump at the beginning of the race, which was created for a 60fps+ computer and now if you use dxtory and limit the fps the jump cannot be correctly cleared. This is a specific case where the fps issue affects the game interpreting the jump more so than usual). The jump cannot be cleared in EvoR either but it's not the "game's fault", or rather the incompatibility is not the "game's fault".
My system is:
Intel i7-3770 @ 3.4GHZ
16GB Ram
Nvidia GeForce GTX 680 with 2GB RAM
Win 7 Ultimate 64bit