> the JS single-thread model really doesn't help. I suspect that this is one of the reasons that the input field used for composing a plain text message hangs

> the JS single-thread model really doesn't help. I suspect that this is one of the reasons that the input field used for composing a plain text message hangs up every 20s - one minute as the backend has to do some IO or the like, even if the input field could be completely independent (e.g., I never see this behavior in Firefox, with much more tabs open and stuff happening in the background) That's just poor engineering and architecture, not an inherent limitation of JS. Modern JS supports multithreading through WebWorkers, see VS code as an example of what a proper editor should be. V8 is an insanely performant engine.