Thanks for the detail perf test, my guess would be lot of optimisation were made since 4.27.
Networking, physics etc and several bugs from ue4, so these improvement lead to some cost in perf in ue5.
Chaos for example like you said is more costly but behave better than physics ue4 and i don’t think we can switch that back in ue5.
You might get more detail from Session Frontend but am not sure if that worth to lead to any conclusion. 