thats because your computer is better for CC than his is.

i prefer to have "slow mo" (one sim update per frame) on, its much smoother for me, and it alerts me to when something is slowing down my CC in a nicer way than a low framerate.

It did a very good job of not being slowed down when I had B21.

but build 22 is a slow and unstable mess, so new rules apply.