marach

It's depressingly true. On another note the Rawbots team have reported a 4-10x performance increase (depending on complexity of the scene) just by switching to bullet physics.

It's actually using them all (you'll find a performance hit happens if you set a CPU affinity) the problem is purely down to physX and the fact that Unity's version is so damn old it's still single threaded and unoptimized (hell it uses x87 instructions something so defunct even Intel tries to deny it exists)

A move to bullet wouldn't actually change /too/ much it's just a bit of a job to add it to Unity (Rawbots has done this for example). Unity itself is pretty flexible and the change wouldn't be too much of a problem causer most likely.

This is actually wrong as well Unity has supported multi-core CPU's for awhile as has KSP (if you check your release notes).