The amount of RAM is irrelevant for SDRAM, since the smallest SDRAM sticks I'm aware of are 16MB - the more important reason for why SDRAM (late-socket 7 motherboards until early-Pentium 4/Athlon XP) is preferred over EDO (late-486 until mid-socket 7) or FPM (mid-286 until mid-socket 7 - both EDO and FPM can be found as 72-pin sticks that are mechanically and electrically compatible) RAM is simply because the thoroughput of SDRAM is significantly higher than both EDO and FPM. Additionally, the L1 cache of socket 7 CPUs has anywhere between twice to four times the thoroughput of 486 CPUs and since this was still an era where L2 cache was on the motherboard, there were improvements with the mobo chipsets combined with lower latency and increased thoroughput of newer cache chips which also significantly improve the performance. Different mobo chipsets can also impact performance, but I don't have enough mobos sitting around to get data that granular. (also I killed the socket 7 mobo that I did the playtesting from Z1M3 onwards, and prices for good socket 7 mobos are stupid on eBay)
So why is that relevant?
For shits and giggles I started doing my playtesting playthrough on a 486 DX4-100 setup (with a good ol' VLB video card and FPM RAM) and I got through Z1M1 and Z1M2, noticing that there was increasing amount of stutter the further I progressed. When I was testing Z1M3, I was noticing atrocious performance with vanilla in
even when using a 1.4Ghz Pentium 3 setup (quick sidenote: L2 cache is now baked in the CPU and running at full speed at this point, so there's no longer a performance penalty between L2 cache on a mobo and a CPU) where it was getting choked hard and continuously stuttering non-stop. Something didn't seem right about that and I told essel about it. A bit of optimising with animated textures happened and suddenly Z1M3 became a lot more playable. I decided to go back and check the start of Z1M2 (as there's noticable delay between being teleported into the main map) and figured out from that what was the minimum CPU and type of RAM required - Z1M2 being a good indicator because it has a ton of midtex work at the start of the main map and 486 CPUs choke on heavy midtex usage, 386 CPUs choke even harder relative to their performance.
My estimate for 32MB is based on the testing before animated texture optimisation - I suspect 16MB would have a small amount of stutter in certain areas. I have picked up a "cheap" socket 7 mobo a couple days ago which has both SDRAM and EDO/FPM slots, so I can do a bit more testing for whether there's a difference in the stuttering for texture/flat heavy areas like Z1M3. I'll get to that soon(tm)