For some programs, that hasn't changed. I use OneNote heavily to write some sort of personal info database I always look up when I forget something or need to reproduce a command verbatim quickly. The act of writing it and organizing the data also heavily reinforces my ability to memorize thing in my mind in and of itself too. So I'm quite fond of that little program.

When I tried to use it while learning Chinese I ended up having to turn off the spelling/grammar correction. It just can't function with two languages in the same notebook. All the Chinese text had the red squiggly lines warning you of a mistake and I found no way to enable the support for more than one language. You must select /one/ language for the spell checker in that program.

Or disable the spellchecker, which is what I did in the end.

But that the "cost" to do so, isn't what's technically required to improve it. You can achieve all these improvements, solve all these problems, probably without much more resource usage. Or negligible added resource usage.

Therefore my conclusion is that the reason e.g. slack usage x1000 what my old IRC or Jabber cliënt used, isn't technical. It's a deliberate choice made for reasons of budget, time to market or another trade-off.

I'm certain that Slack could build a client that does all what slack does, in a client that's hundred(s) of times snappier, smaller, less CPU and memory using. But probably not with their current pace, budget, team or wages.

The newest macOS still needs more memory and suffer bloat but 8GB is still perfectly useable if you avoid google chrome. 8GB is also perfectly usable for Linux too.