Re: Emacs/prelude: lag in opening big files

[Eli Zaretskii]

> From: Vikas Rawal <vikaslists@agrarianresearch.org>
> Date: Fri, 21 Jul 2017 07:37:55 +0530
> 
> I am having a strange problem that I have never faced before.  When I open 
> (C-f) a large file, it gets stuck for a long time. I have to wait for 
> eternity before the file would open. But if I C-g and cancel the process, and 
> do it again, the second time, it opens in a snap.
> I have tried it with many files, and it happens each time. If a file is 
> opened and closed, and I want to open it again, emacs does the same thing all 
> over again. That is, slow to open first time, but opens in a snap if I C-g 
> and start again.
> 
> How do I debug this? I tried to use profiler to figure out where was emacs 
> stuck. Below is the main part of the report on cpu usage when I tried to open 
> a large org mode file. Looks like helm is one of the culprits. Is this usual? 
> Is there a way to deal with this?
> 
> Vikas
> 
> 
> 
> 
> - command-execute                                                6903  57%
>  - call-interactively                                            6903  57%
>   - funcall-interactively                                        6575  54%
>    - helm-find-files                                             6575  54%
>     - helm-find-files-1                                          6575  54%
>      - helm                                                      6575  54%
>       - apply                                                    6575  54%
>        - helm                                                    6575  54%
>         - apply                                                  6575  54%
>          - helm-internal                                         6575  54%
>           - helm-execute-selection-action                        6103  50%
>            - helm-execute-selection-action-1                     6103  50%
>             - helm-find-file-or-marked                           6102  50%
>              - apply                                             6102  50%
>               + #<compiled 0x40bf3dad>                           6102  50%
>             + helm-get-actions-from-current-source                  1   0%

You stopped expanding the profile too early: you should continue
expanding "#<compiled 0x40bf3dad>" and the levels below it, until you
find a significant change in the percentage -- that is where most of
the CPU processing is spent.  (My guess would be it's
org-indent-add-properties, but that's just a guess.)  For more
accurate profile, load all the libraries involved in this as *.el
files, not as *.elc.

(This should probably be a bug report.)