[BUG] cachix.org very slow with dark reader

Describe the bug

It takes 6 seconds for network resources to begin to load. Here is with dark reader enabled. See the output of firefox’s network inspector:

Notice how some resources are delayed, the first being google fonts, until the 5 second mark.

And then if I disable dark reader there is no such delay:

Steps to reproduce

• Open new firefox tab
• Open network inspector
• Ensure dark reader is on
• Go to https://cachix.org/
• See that some resources aren’t loaded for 5 seconds
• disable dark reader
• Open new firefox tab
• Open network inspector
• Ensure dark reader is off
• Go to https://cachix.org/
• See there is no delay

Expected behavior

• Open new firefox tab
• Open network inspector
• Ensure dark reader is on
• Go to https://cachix.org/
• Ideally there is no delay in loading resources, but if this feature requires blocking, I’d say something more reasonable than 5 seconds

Actual behavior

See reproduction instructions.

Screenshots

Screenshots added inline (hopefully) for better readability.

System Information:

• Mozilla Firefox 69.0.1
• system: "x86_64-linux"
• host os: Linux 5.4.44, NixOS, 20.09pre228622.029a5de0839 (Nightingale)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.3.6
• channels(cody): "home-manager, nixos-unstable-20.09pre228622.029a5de0839"
• channels(root): "nixos-20.09pre229870.22c98819ccd, nixos-unstable-20.09pre229870.22c98819ccd"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

Additional context

I first thought this was a problem with cachix and filed cachix/feedback#14, but then figured out disabling dark reader resolves the performance issue.

[domenkozar]

Best to raise that with https://github.com/fomantic/Fomantic-UI

[Gusted]

Or we going to put checks in place(if possible not sure as we can break webpages trough it) to check if we need to analyze the image or not.