> slightly beefed up (say, dual or quad CPU) typical early ‘90s gear.

Early 90's Intel was the 486 33 Mhz. It barely had enough performance to run the TCP/IP stack at a few hundred KB/sec, using all of the CPU just for that task. I think you forgot how slow it was. Pentium II is where it starts to get reasonably modern in the late 90's. Pentium Pro (1995) was their first with multiprocessor support. It was moving so fast back then that early/mid/late 90's was like comparing decades apart at todays pace of improvement.