As someone who regularly uses old Mac emulators on modern hardware, most programs are hundreds of times faster (despite emulation overhead). As someone who regularly uses an actual old PowerBook 2400 from 1997 for fun, I can say that Photoshop 4 is by far snappier on that than the latest Photoshop CS on my MacBook Pro...
This is depressing, but hardly surprising. The dedication to "just ship it" has really built up. The market pressure to build efficient software approaches zero.
All software will approach "human speed," whether it's adding two integers or getting near instant predictions from a GAN. All available resources will be used until it's "good enough. Just ship it," and efficiencies will multiple as in any natural selection: defensive measures like "confusing code," and "unrelated system fails when this one is changed" allowing mostly harmless dumb code to survive and propagate.
Some intrepid learner comes to study the code one day. "Huh, I guess this is how you're supposed to do it. Seems kinda weird but I'm sure it was written this way for a reason. It's been like this for a decade!" And so they copy the procedure into their greenfield project.
Efficient code will always be sacrificed to the god of "Just Ship It" as long as the overall performance is "Good enough." And why not?
Only if you really have to use modern software (which, admittedly, we all have to from time to time). Vim, my terminal, grep and GCC are faster than ever!
To really enjoy computers the trick is to run old software on modern hardware.
