I remember that Quake was not designed to run on a 486 at all. The vertex transformation code that did a perspective divide was optimized around the Pentium mic

I remember that Quake was not designed to run on a 486 at all. The vertex transformation code that did a perspective divide was optimized around the Pentium microarchitecture and wasn't as efficient on other microarchitectures, sometimes much less efficient. Quake is cited as one of the reasons why Cyrix disappeared.