How can I find out what's causing Doom Emacs to start up and run so slowly?

[oodzchen]

I confirm that...

• I searched the FAQ, issue tracker, discussions board, documentation, and wiki, and did not find an answer to my question.

• Any discussions with or conclusions derived from the use of LLMs will be omitted from my question.

What is your question?

I recently reinstalled my operating system, which of course meant I had to reinstall Doom Emacs as well. After the reinstallation, I found that Emacs starts up extremely slowly, taking 3 to 10 seconds each time.

Even after it successfully launches, I can barely do anything. There's a huge delay when I press any keybindings, and it might take up to two minutes before I can even perform some basic operations. The latency is so high that it's almost unusable.

When I start Emacs with emacs -q, everything is normal and there are no issues. I tried using benchmark-init to find the cause of the slowdown, but the results were very brief. It showed that the face-remap module took 22ms (the slowest), followed by my custom theme at 5ms, and then ~/.config/doom/custom.el at 2ms. That was it. The sum of these times is obviously much, much less than the actual startup time I'm experiencing, so I can't pinpoint the real source of the problem.

Before I reinstalled my system, Doom Emacs was much, much faster. With the exact same configuration, it would be ready to use in just 1 to 2 seconds. What could have happened?

Here are my Doom Emacs configuration files: https://github.com/oodzchen/dotfiles/tree/main/doomemacs

Here is my system configuration:

OS: openSUSE Tumbleweed
DE: KDE Plasma 6.4.2
Emacs: 30.1

System information

https://pastebin.com/SKLJEbz3

[Kakupakat]

Same here.
There is a bug report for emacs at: https://lists.opensuse.org/archives/list/[email protected]/thread/MNQCQPJ5KSOKYKYXM3FTC7WEYGGRADSR/

[oodzchen]

The difference is that this only happens with my doomemacs configuration. When I switch to a vanilla emacs setup, there is no delay at all. I've also tried using only the default doomemacs configuration, and it was still slow. It seems like the issue lies with the doomemacs configuration itself.

[EyoelYT]

You can use the profiler, with profiler-start, profiler-stop, and profiler-report. Just place this code in the start of early-init.el in the doomemacs configuration

(profiler-start 'cpu)
(add-hook 'after-init-hook (lambda ()
                             (profiler-report)
                             (profiler-stop)) 100)

[oodzchen]

@EyoelYT Already tried that, here's the output

                                                                       2105 100% - ...
                                                                       2105 100%  - doom--startup-modules
                                                                       2105 100%   - let
                                                                       2105 100%    - let
                                                                       2105 100%     - let
                                                                       2105 100%      - let
                                                                       2105 100%       - doom-load
                                                                       2105 100%        - condition-case
                                                                       2105 100%         - load
                                                                       2105 100%          - load-with-code-conversion
                                                                       2098  99%           - require
                                                                       2098  99%            - byte-code
                                                                       2098  99%             - require
                                                                       2092  99%              - byte-code
                                                                       2089  99%               - require
                                                                       2089  99%                - do-after-load-evaluation
                                                                       2089  99%                 - #:eval-after-load-helper
                                                                       2089  99%                  - #<interpreted-function 425>
                                                                       2089  99%                   - if
                                                                       2089  99%                    - progn
                                                                       1775  84%                     - let
                                                                       1775  84%                      - doom-startup
                                                                       1775  84%                       - if
                                                                       1775  84%                        - progn
                                                                       1775  84%                         - doom--startup-modules
                                                                       1775  84%                          - let
                                                                       1775  84%                           - let
                                                                       1775  84%                            - let
                                                                       1775  84%                             - let
                                                                       1775  84%                              - doom-load
                                                                       1775  84%                               - condition-case
                                                                       1775  84%                                - load
                                                                       1775  84%                                 - load-with-code-conversion
                                                                       1774  84%                                  - require
                                                                       1758  83%                                   - byte-code
                                                                       1758  83%                                    - require
                                                                       1720  81%                                     - byte-code
                                                                       1720  81%                                      - require
                                                                        661  31%                                       + defalias
                                                                        381  18%                                       + byte-code
                                                                        243  11%                                         read
                                                                        220  10%                                       + do-after-load-evaluation
                                                                         15   0%                                       + custom-declare-face
                                                                         10   0%                                       + require
                                                                          5   0%                                       + defconst
                                                                          1   0%                                       + defvar
                                                                          1   0%                                         provide
                                                                          1   0%                                     - defvar
                                                                          1   0%                                      + byte-code
                                                                          1   0%                                  + global-set-key
                                                                        314  14%                     + require
                                                                          3   0%               + advice-add
                                                                          3   0%              + advice-add
                                                                          3   0%              + custom-declare-face
                                                                          4   0%           + advice-add
                                                                          3   0%           + internal-macroexpand-for-load

Still don't know what it means. And now I've switched back to the vanilla emacs configure, everything works fine now.

[EyoelYT]

That is the function call stack with the percentage of cpu time that they take. It is definitely the doom modules.

Maybe it is a dependency issue of some sort? I'm not sure.

You can also do the same thing to check what is taking so long between keybinds (with M-x doom/toggle-profiler). Toggle it on, do the activities you want to look into, then toggle it off, and see the cpu profiler report.