TRAMP users: slowness got you down? Check vc-handled-backends.
reddit / emacs

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patrick_thomson · 2022-10-20 16:32

I use TRAMP to connect to GitHub Codespaces via my
[Codespaces](https://github.com/patrickt/codespaces.el) package.
However, I noted recently that my TRAMP sessions were suffering
tremendous and unignorable lag when navigating within a file. I went
through my enabled modes one-by-one and was surprised to learn that
`vc-mode` was, in this case, the culprit. Setting `vc-handled-
backends` like so:

    (setq vc-handled-backends '(Git))

had a profound effect on latency. I'm not sure why this is the case,
but its original value holds a bunch of entries for VCSs that died
decades ago (CVS, SCCS, RCS…): it's possible that one of my packages
was using all of `vc-mode`'s backends.

My TRAMP sessions to Codespaces are now as responsive and fast as if I
were to connect to them via VS Code. Hope this helps someone!

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glg00 · 2022-10-20 16:52

I personally use:

    (defun my-vc-off-if-remote ()
      (if (file-remote-p (buffer-file-name))
          (setq-local vc-handled-backends nil)))
    (add-hook 'find-file-hook 'my-vc-off-if-remote)


I don't use vc-mode, but still need it on my local machine to use
project-mode; this disables vc when remote.

Another optimization I recently started using:
    (setq remote-file-name-inhibit-locks t)

this inhibits .#<...> lock files. ymmv if you use different emacs
processes to edit the same file, which I never do.

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patrick_thomson · 2022-10-20 16:57

I didn't know about `remote-file-name-inhibit-locks`. Thanks for the
pointer.

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HM0880 · 2022-10-20 17:40

Wow, thanks for this!  It's now part of my `init.el`.

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redguardtoo · 2022-10-21 00:15

Aslo see https://www.reddit.com/r/emacs/comments/4c0mi3/the_biggest_pe
rformance_improvement_to_emacs_ive/

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polaris64 · 2022-10-21 08:52

What perfect timing! I ran into this issue using TRAMP with a slow FTP
server only yesterday and I had "Look into a solution" on my to-do
list. Now marked as DONE :)