It is not my place to justify why modern software is so inefficient, pointing the finger to Windows 10 in particular as if it's an outlier.
Why are YOU using inefficient languages, heavyweight virtual machines, GB sized binaries, Electron and Javascript to write your applications? Why is your boss asking to add feature upon feature upon feature? There is a reason we're in this place, but until then, my point is, stop complaining everything is slow on your old PC. You know exactly why that is, and it is your fault as much as mine.
It's because of us, software engineers, that everything is slow, so it is completely hypocritical that on HN of all places one has to explain that sadly to run modern software one needs modern hardware.
We've put ourselves in this situation and now there's a lot of surprised Pikachu faces around, complaining about Windows getting slower and alt-tabbing to their day job writing yet another crappy Javascript abstraction layer on their shiny M1 MBP.