This also seems to affect the speed of which drivers "recover" from pitting, in our race right now, I had a guy with 50% tyres (medium) and guys in front of him pitted, and on the second lap they were already as fast or faster than my guy (and there shouldn't be noticeable difference in the skills of driver or level of car). Just if this helps to locate the problem.
You might want to check out the MJL league this evening at China. Jason @ Carpers came second. He wasn't able to setup and went default until the first stop. It was by far and away his best result so far. Definitely the no setup bug.
I'm happy to report that we have figured out the issue and will be applying the fix tomorrow to the live site. An announcement will follow when the patch is put live.