I really have problems with Sublime Text's autocomplete, to such an extent that I can't quite be sure whether it's a net gain or loss. If I was sure either way, it wouldn't be a problem, of course — I'm pretty sure it's easy to turn off altogether, if that's what you want.

A common example is copying some PHP source code into a new file, then entering "<?php" at the very top of the file. If I'm working quickly and do the natural thing (i.e. hit ENTER afterwards), I end up with "<?phpversion" and I either have to manually delete it, or do a cmd-z dance. Or I have to remember to press RIGHT after "<?php" instead of ENTER.

Many other similar examples (quote characters often seem to cause a problem). But, on the other hand, I know I've made use of autocomplete to help me type a long constant name which happened to be in the same file. So ... swings and roundabouts.

It isn’t doing the quote matching to save on your typing, but to keep your scanner from providing the wrong tokens to the parser of your compiler that is running all the time while you are typing.

'Only' quoting: 'Serious visual noise'

'I think there are very real costs.'

First off all, "misuse" of autocomplete can be very annoying. Some autocomplete system autocompletes with you.

IN ORWELLS REALITY: It isn’t doing the quote matching to save on your typing, but to keep the scanner from providing the wrong tokens to the parser of a compiler that is running all the time while you are typing.

So... 'Human Interface' ? ^^

If you want the compiler to be useful while you are typing, then the designers of your tooling have to do something. You can argue that they are doing the wrong thing, you can argue that having the compiler running while you are typing isn't worth it because you don't need the feedback, but don't misidentify why they are doing it; they aren't doing it to help you save a millisecond on typing, that isn't the concern at all.