About that part... Modern computers are insanely fast. How does every single piece of software manages to fill half a minute of CPU or disk I/O for enumerating some 3 or 4 items?

It's absurd.

I use Firefox inside eatmydata nowadays, because it spends 10 minutes enumerating the same 2 directories every time it starts up (hundreds of thousands of times). The start menu and equivalents everywhere are already famous. Windows can't search files nowadays, not only it doesn't work, but it never ends either... The list is endless.