Re: File path completions: strange speed discrepancy

[Michael Albinus]

JD Smith <jdtsmith@gmail.com> writes:

Hi,

> I’m trying to debug a very strange issue I’ve encountered when using
> completion UI’s like vertico, selectrum, and fido to navigate remote
> file paths with tramp (over SSH).  It also occurs (I believe) during
> normal tab-driven file completion, but isn’t as obvious there.
>
> Here’s the issue:
>
> When navigating a remote SSH host’s files, starting with find-file
> from a non-remote buffer (like *scratch*), completion is very slow,
> with each key event taking ~1/2s or so.  Very strangely, in exactly
> the same session, indeed with the same (controlmaster’d) SSH
> connection to the remote, C-x C-f starting from a remote file or dired
> buffer is very fast — new completions come in almost instantly.

I've tried it with Emacs 27.2 as provided by Fedora 34, and the builtin
Tramp 2.4.5.27.2. Starting with

# /usr/bin/emacs -Q -f fido-mode /ssh:fencepost:

I can see the problem. However, when the completion is slow, results are
shown when I navigate with <left> and <right> keys. When I use

# /usr/bin/emacs -Q /ssh:fencepost:

(TAB-based completion), I don't see significant differences between
starting from the *scratch* buffer, or from a remote buffer.

I don't use completion styles, so I cannot be of further help. Tramp is
agnostic to completion styles, it provides just the implementation for
`file-name-completion' and `file-name-all-completions'.

I propose to write an Emacs bug report.

> Thanks for tramp.

Best regards, Michael.