Re: Typing latency

[Maxim Nikulin <manikulin@gmail.com>]

On 11/02/2021 23:59, Ihor Radchenko wrote:
> Maxim Nikulin writes:
> 
>> It is not namely typing latency, but I have noticed lags while moving
>> over collapsed headings with "up" key (with "down" it is not so
>> apparent) e.g. in overview view. It has happened after linux upgrade,
>> emacs version changed from 25.2 to 25.3, system package with org mode
>> updated as well. The org file has significant size: 50k lines, 2Mb. I
>> have created a LXC container to compare performance with older emacs. It
>> is quite strange. With org version from git, emacs version is not really
>> important, flyspell mode is irrelevant.
> 
> You can try feature/org-fold branch aiming to address issues with
> performance on large files https://github.com/yantar92/org

Ihor, I have seen the thread with discussion of your branch. This case I 
was surprised the simple move to next or previous currently displayed 
line could be slow. I would expect that emacs has information (in some 
internal structures) what position in the buffer is related to the same 
x coordinate on the previous or next (visual) visible line. Ideally it 
would not depend on how much text is hidden by overlays, properties, 
etc. and should work instantly.

Update to my results. I suspected some problem with loader and I have 
realized what actually had happened. I believed that -L (--directory) 
emacs command line options have precedence and used the following command

     emacs -L ~/org-mode/lisp test-file.org

actually -L processed after init.el file, so (require 'org-protocol) in 
the init file loaded some files from org-9.1.6 (elpa-org system package) 
then remaining files were loaded from git HEAD org version. Even 
org-submit-bug-report did not worked, I tried it to get summary of 
actual configuration. I do not run emacs in such way routinely, so the 
problem was specific to my tests.

My current impression that in both cases of emacs-25.2 and 26.3, with 
org from git moving cursor over collapsed headers works faster than with 
org-9.1.6 or org-9.3.1 from elpa-org package. In all cases 
line-move-visual dominates in profiler reports.

So slow down I have noticed is likely related to growth of the file size 
rather than to system upgrade. I just mostly navigate through the file 
using C-u C-c C-j, so I just was not using cursor keys in overview tree 
display for some time.

So strange observation, due to that I sent previous message, is 
explained: incorrect usage of command line option during tests. My 
complains related to performance is not related to emacs upgrade, org 
master branch HEAD from git works better. Maybe later I will try 
suggestions how to improve performance or I will just split my file into 
smaller parts.

Sorry for the noise.