Ihor Radchenko <yantar92@posteo.net> writes:

> Christian Moe <mail@christianmoe.com> writes:
>
>> After upgrading to 9.7 (still on Emacs 27.1), I'm seeing very long waits
>> when trying to use tag completion in large files, whether with C-c C-q,
>> %^g in capture templates or running (org-get-buffer-tags) directly. This
>> applies both to 9.7.1 and 9.7.2 (on two different machines with similar
>> environments, both older hardware). On repeated tries I have also had
>> several freezes.
>
> May you please record the CPU profile?
> You can do
> 1. M-x profiler-stop
> 2. M-x profiler-start RET cpu RET
> 3. Query tags
> 4. M-x profiler-report
> 5. M-x profiler-report-write-profile
> 6. Share the saved file

Thanks! I attach a profile report (for a largeish file with 67 tags
across 1515 headings, 17K+ lines, 18–36 seconds wait to get tags).

I thought for a while that maybe advice from vertico-mode was the
problem, but eliminating vertico-mode from the config didn't help;
still, I also attach a profile report from a run without vertico-mode.

I tried starting emacs with an empty .emacs file; it didn't solve the
problem, so I haven't located any problem in my config. (Starting emacs
with 'emacs -Q' did help - but only because it threw me back to built-in
org 9.3.)

I experimented with generating simulated Org documents with varying
numbers of tagged headings (n=500, 1000, ... 5000) and doing
(benchmark-run (org-get-buffer-tags)) in them. The time needed to get
the tags seems to grow polynomially with n^2.

Yours,
Christian