I don't know this fork but as I read it seems just to be some way optimized for older x86 CPUs but still requires FPU, right?
But might give a try on my other machine 486DLC with ULSI MathCo that gave me 2,5FPS in original Quake 😀
On my main PC (Sandybridge 2600K) the speed up of 586quake over original is like 540 vs 430FPS. So I'd expect maybe 3-3,5FPS on 486DLC...
UPDATE: hm, I got only 2,7FPS (+0,2).
Gigabyte GA-P67-DS3-B3, Core i7-2600K @4,5GHz, 8GB DDR3, 128GB SSD, GTX970(GF7900GT), SB Audigy + YMF724F + DreamBlaster combo + LPC2ISA