Subject: bug#48841: fido-mode is slower than ido-mode with similar settings

From: Dmitry Gutov <[email-masked]>
Date: Sun, 4 Jul 2021 04:42:28 +0300

On 18.06.2021 00:29, João Távora wrote:

>> 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.

Turns out that indeed the logic is used in the "multiple matches" case: 
when icomplete-hide-common-prefix is non-nil.

Meaning, with icomplete-mode but not with fido-mode.

> 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.

So I have done the above. There is no change in observable behavior 
either (AFAICS), so it's win-win.