Wouldn't x86 have the higher code density?

https://www.vogons.org/viewtopic.php?t=56207 "Finding an IA-32 CPU most like the MIPS R3000A"

"a 40MHz MIPS R3000 gets 18.1 MFLOPS, while a 66MHz 486DX2 only gets 3.1 MFLOPS. So, the MIPS is downright Pentium-class for floating-point code. For integer code, the MIPS R3000/40 manages a score of 22.6 in SPECINT89, while the 486DX2/66 gets 34.0"

So its also only "Pentium-class" for floating point math, not for integer.

The PSX CPU did not even have floating point support. It's nowhere close to a Pentium 90.

It’s a video game system. You can make do without floating point. The whole “it doesn’t have fp so whobbly textures” is a myth.

It did have a fixed point vector coprocessor instead though.

It should, by nature of CISC. However, the other coprocessors on the playstation meant you weren't wasting all your CPU cycles on rendering, which was the majority of the time on a 3D game of the era.

The CPU in the PlayStation is nowhere near a 90 MHz Pentium.

The CPUs in the Saturn, PlayStation, and N64 were single issue, and could execute at most one instruction per clock. The Pentium was superscalar and could execute two instructions per clock. The Pentium would likely average, for integer operations, more than four or five times the performance. Much higher for floating point.

The MIPS CPU in the PlayStation is much closer to a 486 in performance-per-clock for general purpose code. A similarly clocked 486 might win some G.P. code competitions due to better caches, but the PSX's CPU would smoke the 486 in transform and lighting, thanks to it's DSP coprocessor, and the MIPS would still have much better performance-per-dollar than the 486.

Pentium CPU's often matched the performance of SPARC/MIPS chips clock-for-clock, at least in non-floating point operations. And at that time, almost no games use floating point anyway.