I had a Cyrix 6x86 when Quake first came out. My disappointment at how poorly Quake ran on it was significant, especially because pretty much every other game at the time ran well on the Cyrix. The FPU performance in Quake was doubly handicapped on the Cyrix: not only was its FPU slower than the Pentium's to begin with, Quake's code was indeed hand-optimized for the Pentium's FPU pipeline. Fabien Sanglard's writeup of Michael Abrash's optimizations for Quake goes into great detail: https://fabiensanglard.net/quake_asm_optimizations/
Cyrix was physically incapable of pipelining FPU instructions. Without Pentium Quake would have had to wait two more years for commodification of CPUs delivering similar floating point performance.
Quake needed March 1994 Pentium 90-100 to deliver ~smooth 25fps. Cyrix released similarly performing 6x86MX PR200 in May 1997, AMD K5-PR166 January 1997. Quake was unfeasible till ~1998 at the earliest to be able to sell playable game.
