I commented under another reply, but I've never once experienced actual UI jank/input lag on Slack or Discord. Not once. I don't know what I'm doing differently.
Here's one theory: the web makes it super easy to add lots of little animations to apps. Discord in particular takes lots of advantage of this. Is it possible all the little animations are making things feel slightly less "instant", and being mistaken for input lag? That wouldn't impact typing, but
Having powerful machines would be one thing. I really implore you to try using a low end machine for a while and see how bad the web is. I currently use a 4gb 2015 MacBook Air and i often see Discord and other websites-masquerading-as-apps hogging upwards of 2 gigs of ram which is inexcusable. I can hardly believe that animations would contribute to lag (or perceived lag) especially because we can see a lot of completely native apps that have these "micro-interactions" and still feel fast and responsive.
On the other hand Ripcord, an alternate client for Slack and Discord sits at 50mb of RAM and single digit CPU usage.
Here's one theory: the web makes it super easy to add lots of little animations to apps. Discord in particular takes lots of advantage of this. Is it possible all the little animations are making things feel slightly less "instant", and being mistaken for input lag? That wouldn't impact typing, but