[fwsgonzo]

I actually measured it. It was around 65-85ns for Lua and 55ns for LuaJIT (on a 7950X). It adds up every time you make a call, despite looking like a small value. Of course, you can multiply it by 2-5x when you put it in production.A decent emulator these days should have < 20ns time to first instruction. The worst emulators are the ones that require you to host them in another thread for the purpose of execution timeout using some kind of timed-wait (eg. futex op), adding a massive 10-20 micros overhead just to communicate tasks.

Ultimately the script in a game engine either makes a bunch of API calls, so we want the "system call overhead" to be that of an opaque function call (4ns), and sometimes you share memory in order to read out properties and put abstractions on them (probably not relevant to Lua). So, it's important to get going fast, and to be able to make hundreds of engine API calls without unnecessary costs.

Benchmarks: https://gist.github.com/fwsGonzo/2f4518b66b147ee657d64496811...