emacs is slow when the pdf buffer is large

[Xephobia]

Describe the bug When I read a pdf normally and the buffer is the only one, scrolling is very slow. But if I clone the buffer so that the resulting two buffers are smaller, scrolling is way smoother and faster.

Steps to Reproduce the behaviour

1. Open a pdf
2. scroll

What is the expected behaviour? It should be faster

Desktop

• OS: Gentoo Linux
• Emacs Version: GNU Emacs 29.3 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.39, cairo version 1.18.0) of 2024-03-27
• Poppler Version: 24.02.0

Your pdf-tools install Please complete the following information:

• pdf-tools Version:

     Status: Available from nongnu -- Install
    Archive: nongnu
    Version: 1.1.0
     Commit: a9c9a12c3ecf2005fa641059368ac8284f507620
    Summary: Support library for PDF documents
   Requires: emacs-26.3, tablist-1.0, let-alist-1.0.4
    Website: https://github.com/vedang/pdf-tools/
   Keywords: files multimedia 
 Maintainer: Vedang Manerikar <[email protected]>
     Author: Andreas Politz <[email protected]>

Additional context Here's what I got during profiling:

        5068  96% - command-execute
        4794  91%  - funcall-interactively
        4789  91%   - mwheel-scroll
        4771  91%    - pdf-view-scroll-up-or-next-page
        4762  91%     - pdf-view-next-page
        4762  91%      - pdf-view-goto-page
        4757  90%       - pdf-view-redisplay
        4757  90%        - pdf-view-display-page
         246   4%         + pdf-view-create-page
           2   0%       + internal--before-save-selected-window
           2   0%       + doom-modeline-update-pdf-pages
           1   0%         image-mode-window-put
           9   0%     + image-scroll-up
           8   0%    + pdf-view-scroll-down-or-previous-page
           5   0%      mouse-wheel--get-scroll-window
           2   0%    + run-with-timer
           5   0%   + execute-extended-command
         274   5%  + byte-code
         156   2% + #<compiled -0x726034f3b8bc27b>
           6   0% + redisplay_internal (C function)
           2   0% + timer-event-handler
           0   0% + ...

the pdf-view-display-page function seems to be the deepest one that takes the most time

[nick4f42]

In my case, I was able to speed up pdf-view by optimizing the pdf.