This is not a bug. This is an effect of cache that can be mitigated with solutions provided earlier. If this solution doesn’t fix your problem, provide a PR. I’ll be glad to review it.
EDIT: I don’t see my post that I posted a few days ago.
Anyway, It listed a few options like this 1:
Or use a fixed time step. Ot the solution to swith to dynamic bodies when scene is ready.
Basically, anything to not have the duration time spike at the frame update time.