> Will this impact a big-money gaming rig? Probably not? Will it run good on the Steam Deck? Probably not.

Runs fine on steam deck. Runs fine old on 10 year old PC. It's really not that expensive, if you code it correctly (which means data oriented programming, programming in a cache aware way and going wide for everything to distribute load when possible).

But this is how modern games are coded anyway. See ECS/DOTS for Unity and so on. Based on similar techniques we've been using for a decade+ on game consoles.

> Generally, in a game loop, all this stuff is going to be single-threaded and blocking, right?

No. Once you go above 100 players you usually to go wide for pretty much everything across multiple threads, even on the client. But obviously on the server, you go really wide.