Why do my requests to github.githubassets.com hang?

I’ve had a particularly annoying problem using the GitHub website since earlier in the year. Often, pages will hang while loading and then leave me with things like this: The increasing use of client-side JavaScript on GitHub doesn’t help when this happens That problem is caused by requests for CSS and JavaScript files on github.githubassets.com hanging, with Firefox giving up after a while. That leaves the page with broken styling, missing data and other problems. I can easily reproduce the problem in Firefox on Windows 11 by: Copying the URL for a CSS file on github.githubassets.com (currently https://github.githubassets.com/assets/light-99f877e9ddfc0e51.css works) Opening the Network tab in the Developer Tools in Firefox and ticking ‘Disable Cache’ Loading the copied CSS URL Refreshing the page several times, waiting a few seconds between each attempt It’s often the second or third attempt at loading the CSS file that will hang. It’ll hang for at least several seconds, and…