March 2018
it has happend since the performance update and since then, the stuttering is happening
https://youtu.be/fkxNocu7dcI
March 2018
the reason for that seems to be that you have to many cars, and while watching the video it seems that you buyed like every single car ? i don't think this will change you either have to get rid of unused cars or live with lag.
and while there are only 50wraps and they say they won't change that, i guess the game is designed to only have arround that amount of cars, maybe on purpose or maybe because they already knew that lag will happen.