[HaroldCindy]

One thing that was immediately apparent upon switching VMs was that a lot of the existing overhead was in scheduling, context switching and the implementation of the actual library functions like `llDoWhatever()`.

We haven't even used Luau's JIT at all yet, but preemptive scheduling of what's typically trivial glue code is much cheaper and easier with a VM that supports it as a natural consequence of its design versus transforming everything into a state machine at the AST or bytecode level for a VM that doesn't.

> Actually, the biggest problem is that each idle program uses about 1us per frame, which adds up.

More scheduler overhead to resolve :)

[Animats]

(For those not familiar with Second Life, every object that does something has a little program in it. Every chair you can sit on, every door you can open, and every clothing item where you can change colors has a small program written by some users. Most of those programs are almost always idle. But there's a tiny amount of CPU time consumed on each frame for each idle program, about 1us to 2us in the Mono implementation. A region can have 10,000 little programs, each eating 1us on each simulation cycle, 45 times a second. This adds up.)

[ChocolateGod]

The amount of heavily custom scripted HUDs required to do things in Second Life seems pretty insane last time I checked it, one for a head, one for a body, one for animations etc. I'm surprised the viewer doesn't have a way to "dock HUDs" where they can be activated/deactivated with one click when not in use in viewer managed regions.