Unless I'm missing something and the value does see some use in the
multiple-matches situations, the patch below both keeps the current
behavior and gives the same performance improvement:
That'd be fantastic, but I doubt you'd be keeping the exact same
behaviour. I never understood it -- that's the thing here -- but I
think that completion-try-completion is doing more stuff when multiple
candidates matched by a pattern happen to share the same prefix or
suffix or something like that. I might be completely wrong, tho.
But really if you make this patch conditional to fido-mode or that other
var that you think is more abstract, I think it's fine and it's a very
clear win. I really doubt that the tiny number of fido-mode users care
about that behaviour anyway, but I'm sure they'll appreciate the
considerable speedup.