If it isn't pipelined, then it'll probably be more like a 286 or 386 performance-wise. IIRC, Quake only had a smooth framerate on my 486DX-33 with floating-point support.
Quake should only have worked well on a Pentium because it could execute float instructions in parallel with CPU instructions, or something. At least Quake was unplayable on my 486DX (don't remember MHz, 66 or below). Even Doom was too slow.