I develop very complicated software for a living and as always, there are some features that will take an unreasonable amount of time. On large documents, you have customers wait 5 seconds for a regular operation (that you may need to complete dozens of times in a row).

And yet when you ask customers whether they want more features, or a faster program it's invariably features. Fix a bug or add a feature? Add a feature. Improve perf or add a feature? Add a feature.

My own tolerance for delays is tiny, but my "average users" seem to not suffer from it at all. I guess the reason is this: they know how much time something took before. They know that if this takes 10 seconds and it took them an hour to do on paper, that's quick. Meanwhile for me I'm in the IDE having a 200ms keystroke delay and I'm almost having a heart attack.