Re: follow-mode: extremely slow in combination with org-mode

[Gerald Wildgruber]

On Sa, Jun 16 2018, Eli Zaretskii <address@hidden> wrote:

> There's something here I don't understand.  This profile says that
> follow-calc-win-end calls posn-point via two 'apply' calls, a
> byte-compiled function, and a lambda-function.  But there's nothing
> like that in follow.el that I could see.  Did you advise some
> functions in follow.el?  If not, what are those intermediate calls?

I repeated the profiling two times; the intermediate calls disappeared;
I can't say what might have caused them; here is the result:

- follow-post-command-hook                                      21938  71%
 - if                                                           21938  71%
  - let                                                         21938  71%
   - save-current-buffer                                        21938  71%
    - follow-adjust-window                                      21933  71%
     - if                                                       21933  71%
      - progn                                                   21933  71%
       - let                                                    21906  71%
        - let*                                                  21906  71%
         - progn                                                17609  57%
          - follow-windows-start-end                            17606  57%
           - if                                                 17606  57%
            - let                                               17603  57%
             - let                                              17603  57%
              - while                                           17603  57%
               - setq                                           17599  57%
                - cons                                          17599  57%
                 - cons                                         17599  57%
                  - cons                                        17599  57%
                   - follow-calc-win-end                        17591  57%
                    - let*                                      17591  57%
                     - if                                        9229  30%
                      + let                                      1115   3%
                      + pos-visible-in-window-p                    26   0%
                       posn-point                                8350  27%
                     + window-inside-pixel-edges                   12   0%
            + follow-cache-valid-p                                  3   0%
          + follow-update-window-start                              3   0%
         - if                                                    4297  13%
          - follow-redisplay                                     3329  10%
           - let*                                                3329  10%
            - cond                                               2924   9%
             - follow-calculate-first-window-start-from-above               
2924   9%
              - save-excursion                                   2924   9%
               - let                                             2924   9%
                - while                                          2924   9%
                 - if                                            2924   9%
                  - setq                                         2899   9%
                   - follow-calc-win-start                       2899   9%
                    - while                                      2899   9%
                     - let                                       2899   9%
                      - setq                                     2896   9%
                       - car                                     2896   9%
                        - follow-calc-win-end                    2896   9%
                         - let*                                  2896   9%
                            posn-point                           1455   4%
                            if                                   1441   4%
                        set-window-start                            3   0%
                  + not                                            25   0%
            + let                                                 169   0%
            + follow-calc-win-start                               125   0%
            + follow-estimate-first-window-start                  111   0%
          + let                                                   598   1%
          + setq                                                  364   1%
          + follow-avoid-tail-recenter                              3   0%
          + and                                                     3   0%
       + follow-avoid-tail-recenter                                27   0%
      set-buffer                                                    5   0%


>> > If you "show all" in the Org buffer, do the lags become significantly
>> > smaller?
>>
>> Yes, the difference is VERY significant; but I guess this is because
>> with collapsed headings, there is A LOT more text within the boundaries
>> of my frame, than with show-all.
>
> How much is "A LOT more"?  How many physical lines do you have in
> typical single window in that Org buffer?

When I do a SHOW-ALL, my emacs frame split into those five windows
connected by follow-mode show about 700 lines of (natural language)
text. If COLLAPSED, it can be up to several thousand lines of text
hidden under the org headings (typically two to ten thousand lines).

Gerald.

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