There is some C in the game as well:

It’s 99% written in x86 assembler/machine code (yes, really!), with a small amount of C code used to interface to MS Windows and DirectX.

https://web.archive.org/web/20201108105209/http://www.chrissawyergames.com/faq3.htm

Yeah, Quake 2 recommended a Pentium 133, and that was released two years earlier(the AMD equivalent was released only a year and a half before the game). It required a Pentium 90 which was three years old, but it didn’t run smooth from what I remember.

That sort of requirement for a major component today would be considered self-sabotage for most non-vr pc games.