Entering and Exiting the Pits

I dont know if this has been discussed before and it is not a major issue as it is the same amount of time for everyone who enters and leaves the pits, but the constant juddering of the cars sometimes nearly stopping is a gripe and it has been the same since i can remember, is there a reason for this?

Last night, I entered the pits in an SUV and I must say it was hilarious the way it was moving. In fact, I would say it looked like the vehicle had picked up an orgy while in the pits and they were putting in the vinegar strokes on pit exit. The car looked like a space hopper.