Why does it follow that software designed for modern hardware, running on modern hardware, should be slower than software designed for older hardware running on slightly newer hardware?
The only significant difference in priorities as regards speed would be the modern prioritization of "developer time", ads, and telemetry.
I can run Windows 95 applications at better than era-appropriate speed, in an x86 emulator written in javascript running on a web browser. That's at least 3 layers of virtual machine abstraction and the applications are still faster.
So if you're saying "the comparison isn't fair because modern software is too shit to hold up", then I agree, but if you're trying to tell me there is something else inherent to modern computing that makes software so many orders of magnitude slower, than I request that you show data to support that claim.