Re: Too long completion delay time in LISP interaction mode.

[Tassilo Horn]

Hongyi Zhao <hongyi.zhao@gmail.com> writes:

> On Ubuntu 20.04.3 LTS, I'm using the self compiled Emacs git master
> version. I find there is a very long completion delay time in LISP
> interaction mode. For example, when I type `(map)' in scratch buffer,
> there will have 5070 candidates as shown in the attached file, and the
> completion delay is about 2-5 seconds.
>
> Any hints to improve this phenomenon?

First, I'd try to isolate where the slowdown happens.  The screenshots
suggests you are using company-mode with custom hacks to get the
numbering of candidates and you are using some fuzzy completion-style.

So I'd start with emacs -Q and typing (map<TAB> in *scratch* to get the
*Completions* buffer.  That will probably be fast but deliver less
results because of the default value of `completion-styles'.  Then I'd
try out your settings of `completion-styles' (and
`completion-category-overrides' if you have customized that).  Then
again with `company-mode' but first without the numbering hack, and
eventually with it.  At which step does it become slow?

Also, using the profiler might shed some light on where the time is
spent, see (info "(elisp) Profiling").

HTH,
Tassilo