Multitasking

I'm wondering if ComputerCraft actually does multitasking (I know it doesn't on a single CC computer). I feel like I've heard things about, though CC uses threads, it only running one at once. I'm trying to decide whether or not it would be worth it to make a bank of computers to allow executing processes faster (rendering 1300+ points from 3d to 2d (using OpenPeripheral Terminal Glasses) is kinda slow, as is 1900+ for drawing a terminal with Terminal Glasses)

Although it uses threads, it doesn't execute more than one Lua co-routine at a time. While one computer is running code, all other computers are yielding. Therefore, at least within ComputerCraft, clusters are less efficient than single units as parallel processing is impossible.

Well that sucks, makes me wonder how popular servers manage to run CC computers at any decent speed though. (maybe people just aren't doing the ridiculous sort of things I like to do)
Is there any reason it's implemented as such?

Presumably it's so that ComputerCraft doesn't monopolise MineCraft server power, as it should theoretically put an easily managed cap on CPU usage.

I suspect it doesn't quite work out like that, but generally it should mean that if your world is laggy ComputerCraft isn't the culprit.