Game sets processor affinity to 2 cores out of 8

[Seraph522]

It's a 32-bit game; is it possible that's the reason? It'll become a 64-bit game with the launch of Shadowbringers.

Actually, the game is already 64-bit if you're running it in DX11 mode; it's only 32-bit in DX9 mode (I think the launcher's still 32-bit, though). They're dropping support for DX9/32-bit OSes in Shadowbringers, not making the game 64-bit.

OP, are you running the game in DX11 mode? If it's in DX9 mode, that may be part of the reason, though I'm not 100% certain. It does seem a little weird, though; I have an i5-8600k in my system, and it's defaulted to using all six cores.