Not sure where you're getting at. MS Word, full load to ready state after macOS reboot takes ~ 2 seconds on my M1 mac. If I close and re-open it (so it's on fs cache) is takes about ~1 second.

You, and sibling comment author just never experienced the truly responsive ui.

It is one where reaction is under a single frame from action. EDIT: and frame is 1/60s, that is 16.(6)ms. I feel bad feeling I have to mention this basic fact.

This was possible on 1980s hardware. I witnessed that, I used that. Why is it not possible now?

I've used 1980s hardware. In the 80s. And used UNIX and HP/Sun/SGI/etc hardware since the 90s. Not only it was no "truly responsive", nothing opened in a "single frame" (talking about X Windows). Took way longer then 1-2 seconds to open a browser on a blank page for example, and for many programs you saw them slowly drawing.

And I did. And it did. Like, Amiga, even 500 models.

I do not doubt X was horrible from that pov. I remember R5. This is not that I meant.

edit: there were no web browsers back then. the effin "folder browser" opens slower on my xfce4 than the same in an a1200 emulator in a window next to it. this is sad.

Probably rose tinted memories. Here are actual Amiga 500 speeds:

https://www.youtube.com/watch?v=Tl6092fMkZY

Not only it takes a second just to redraw a moved window (with mid-way frames and flashing in between), opening a tiny program is slow and shows the "zzz" busy indicator.

Base model M4 Mac Mini -- takes 2 seconds to load Word (and ready to type) without it being cached. Less than 1 second if I quit it completely, and launch again, which I assume is because it's cached in RAM.