> I think users have a performance budget and once you are inside that budget, there are rapidly diminishing returns for faster speed.
"Budget" is kind of a strong word. For non-hard-real-time systems, there are various points of diminishing returns on an exponential curve. However, very few interactive programs I've ever used have ever gotten to an acceptable point on that curve, given their features and the performance of my hardware. Android should not take three seconds to drop down the top drawer on a Snapdragon 617. Flutter should not introduce a noticeable latency for typing ASCII characters. Emacs should not take several seconds to display my which-key bindings. Gmail should not take ten seconds to load.
> If people don't complain there's probably better places to spend engineering effort.
For the majority of software, what's actually happening is that people don't realize that "better" is even possible.
> the slower speed is traded off for something: a safer abstraction, faster development, features the users are requesting, better security, etc.
You can make better tradeoffs, and you can make worse tradeoffs. The vast majority of modern software trades off an unacceptably large amount of performance for an unacceptably small amount of all of those things, to the point where those aren't tradeoffs - they're excuses for abysmal engineering discipline.
Additionally, most of those tradeoffs aren't actually necessary. Rust gives you speed, memory safety, and some better security all at once. Common Lisp gives you speed, memory safety, better abstractions, and faster development time. The vast majority of features shouldn't actually have a performance penalty if not being used - for instance, if I don't use the "export to PDF" feature in an office suite, there's absolutely no good reason for it to have any performance impact aside from possibly a few milliseconds of startup time. Finally, the vast majority of software slowdowns that I've experienced have had nothing to do with security at all.
> I think some of us on HN have higher expectations for software performance than "normal" users
Or we're much more aware of what hardware is actually capable of.