The amount of money spent on software development was a lot smaller and there were far fewer programmers. And they were creating a lot of bloated nonsense that you could install on your 8086, commodore 64, or whatever. Windows 1.0 is a good example. That was released nearly 35 years ago.
These days the one thing that's different is that hardware ages a lot slower. I've been on several laptops with 16GB since 2012. Back in 2012 that was a lot. Now Apple seems to still find 8GB more than enough for anyone (Bill Gates pun intended). Things are moving much slower with hardware.
I remember reading years ago about how people kept asking microsoft's engineers why Visual Studio hadn't been updated to be a 64 bit native app. They said they didn't need to - if visual studio ever gets anywhere near the 3gb memory limit (or whatever it is) on 32 bit windows apps, they spend the time to optimise the application. As a result, there is / was simply no benefit to have the program running in 64 bit mode. Even for massive projects, it simply doesn't need the larger address space.
Nowadays,hardware performance is increasing at 10% per generation https://www.cpubenchmark.net/singleThread.html
With today’s hardware and today’s cost of software engineers…
Do you see your hardware getting significantly better at each gen?
These days, you have the real possibility the program(s) have a limited life span before the next upgrade. With today's hardware, you can bet you will get more performance per $ spent than by changing the software.
IIRC, I think RMS said something like "do not worry about performance, hardware will catch up". In the case of Emacs, it definitely did.