PDF/DJVU viewing unuseably slow in emacs 28.1.

Does anyone know why this is and whether I can do something about that? Zathura is bleedingly fast by comparison. However I want to switch to Emacs since apparently it can do annotations in PDFs and DJVU files. The problem is that whenever I open either type of file Emacs immediately maxes out my CPU and basically stops, forcing me to kill it.

Difficult to offer thoughts without more details of your setup. Are you using stock Emacs, or a distro like Doom? In what context/OS? What relevant extensions do you have enabled? Is your configuration set up to do certain things when opening files? And so on.

It's mostly stock Emacs. It's the standard Void Linux package. I'm not sure which extensions would be relevant honestly and if anything happens when files are opened I do not know about it. I haven't set anything like that up myself. I do use Evil, and I have Ivy, Helpful, and use-package installed additionally. Is there anything else I can/should check for?

So you're viewing PDFs with doc-view-mode, i.e. is that the mode you eventually end up in when viewing a PDF? (i was previously on Void, and never had the sort of issues you describe, although that was prior to 28.1.) Have you tried starting Emacs via `emacs -Q` and checking if the problem is still there?

It seems like it's doc-view-mode, at least the modeline says "DocView". Yeah, Void is generally pretty good. :) Okay, I tried `emacs -Q` now (I didn't know about it before) and the problem doesn't occur. So it would seem like it's something in my config? How do I go about debugging that? Do I just comment out packages until I find the one causing the issue?

Yeah, either that or bisecting (removing one half of your config, checking what happens, repeat with the remaining half), depending on the size of your config. Void is indeed a pretty good distro! i only moved to Gentoo relatively recently, because i've been using Linux systems long enough to be able to want to specify "Don't need *that*, but do want *this*", etc.

If you're using docview-mode, try setting up [pdf-tools](https://github.com/vedang/pdf-tools). It's much faster.

So after some testing it seems that linum-relative is the problem. Not sure what to do about that. I used to use Gentoo years ago and it's great. I like Void for it's low effort though. There it's much that ever requires attention. But I'm thinking of trying out Source Mage sometime. :)

This seems really useful thank you! :) Do you happen to know of something similar for DJVU files?

\*nod\* That seems plausible, as doc-view-mode already disables other line numbering stuff, as per `doc-view.el`: (setq-local global-linum-mode nil display-line-numbers-mode nil) This is the sort of thing you can deal with via a hook, when one has been provided; add to your config something like: (add-hook 'doc-view-mode-hook (defun my-doc-view-function () "Function to run when doc-view-mode starts." (linum-relative-off))) The function can be removed from the hook with: (remove-hook 'doc-view-mode-hook #'my-doc-view-function) Hadn't heard of Source Mage! Will read up on it, thanks. :-)

Nope. I imagine docview-mode can handle them. But as you've discovered it can be slow.

You might want to have a look at EAF for fastest pdf viewing experience.