Windows95 was decent even with 8 MB, on a 66 MHz or 100 MHz 486 CPU.

With either 4 MB or only a 386 CPU, it was definitely crippled, making an upgrade not worthwhile.

Windows 95 on a 386 CPU with enough RAM was alright. Not fast but very useable.

https://youtu.be/Pw2610paPYM?t=72

But most 386 didn't have 8+ megabytes, and some 386 had a 286 like data bus, making it even slower. (386SX)