AI pit stops are much shorter than mine

[Flual]

Hey.
I did a 90 minute race at Classic Le Mans. It takes me one Minute to fill up the tank of my car. The AI in the same car pits for 20 seconds, so I'm losing 40 seconds every pit stop. This is not very enjoyable.
Is this a known issue? I cant find any solution for this. I tried to disable the acclelerated fuel consumption but this also didn't work.