My old boss was in the video game industry from the late 90's until 2017 or so and would talk about this a lot.
It's less about old games being optimised so much as modern non-game software being mind-blowingly wasteful.
Modern, well optimised AAA stuff like Doom 2016 or The Last of Us 2 is as much a work of genius design (if not more) as Rollercoaster Tycoon or Warcraft II. If anything, Vulkan is bringing us closer to the metal than ever before.
It's just a general shift in consumer expectation over time. There is no longer any pressure for regular apps to be performant, so they aren't.
Before the late 90's it WAS about games being optimized. The earlier, the more optimization was required.
An example I like to use is Elite on the BBC Micro computer. They fit 8 galaxies of 250 stars each with a planet with its own economy, and a space station, along with real-time 3D wire-frame space flight with hidden line removal in less than 32KB of RAM on a 2 MHz 8-bit 6502-based system. It was incredible for its time. For me, it was more incredible than DOOM when it came out. I found Quake a lot more impressive than DOOM.
The second version written for the IBM PC was coded by hand in assembly language by the same programmer who coded Rollercoaster Tycoon, mentioned by the OP above.
It's less about old games being optimised so much as modern non-game software being mind-blowingly wasteful.
Modern, well optimised AAA stuff like Doom 2016 or The Last of Us 2 is as much a work of genius design (if not more) as Rollercoaster Tycoon or Warcraft II. If anything, Vulkan is bringing us closer to the metal than ever before.
It's just a general shift in consumer expectation over time. There is no longer any pressure for regular apps to be performant, so they aren't.