Re: Very slow getting tags for completion after 9.7 upgrade

[Ihor Radchenko]

Christian Moe <mail@christianmoe.com> writes:

> 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 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.

The underlying also is NLogN, not N^2. And it cannot be avl-tree that
shows up in the profile - avl-tree code is built-in and it is
well-tested, with NLogN worst case complexity.

What is fishy is that GC takes 80% of the time. It is not normal.

May you try to clear ELPA directory completely, start emacs -Q, and
install Org mode? Just to make sure that there are no issues with mixed
compilation.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>