You will not beat SumatraPDF for speed of opening & reading PDF's.
I’d recommend using a dedicated PDF reader in any case.
One advantage of Firefox's PDF reader is that it is sandboxed which a dedicated PDF reader typically isn't AFAIK.
Generally speaking most dedicated PDF readers haven't implemented the nastier parts of the PDF spec that need a sandbox. Except adobe. They support everything because they wrote it. But they keep making it worse so I can't recommend them.
For Linux users, SELinux's sandbox command works well. (The manual isn't event two printed pages.)
I think flatpacks also have some sandboxing.
Re:Hang on to Your Firefox
by TremendousJudge on Tuesday September 01, 2026 @06:53PM
(#49529391)
I use SumatraPDF for reading, but it doesn't do editing. The Firefox PDF editor works perfectly fine.
In latest pre-release it does editing too (annotations, filling out forms, extracting pages, deleting pages etc.)
Re:Hang on to Your Firefox
by lern_too_spel on Tuesday September 01, 2026 @09:25PM
(#49530620)
If you're going to use a Chromium based browser, why pick one that's filled with crypto ads? I use Firefox on mobile because it supports extensions. One of the main benefits of the web is that, unlike proprietary native apps, I get to experience it the way I want. The web is nearly intolerable without extensions.
Enable background updates when Firefox is not running[1]. This way it will be ready to launch anytime.
https://support.mozilla.org/en-US/kb/enable-background-updat...
My current main browser across desktop and mobile is Brave. Pretty happy with it. Overall more efficient and with a better UI than FF. I've used FF for many years, but I feel it's simply not as good as competitors anymore.