Yes! Obviously long-running operations should be asynchronous, but the assumption that all operations should be treated as long-running is wrong. Specifically,

Yes! Obviously long-running operations should be asynchronous, but the assumption that all operations should be treated as long-running is wrong. Specifically, typing feedback and button feedback should be synchronous, and should be done directly in the UI loop. I understand the rationale for going async -- you can never be sure exactly how long anything will take, and invisible things like memory management and caching can blow up your runtime; and if you get synchronous operations wrong, that leads to spinning beach ball cursors and “app not responding” errors, which are even worse than lag. But in that scenario, an async app isn’t going to perform any more usefully, you’ll just get a blank or frozen screen instead of a beach ball.