Problems I’ve encountered recently:

• Pages often take tens of seconds to load, even on a stable internet connection.

• Using the back/forward buttons takes a few seconds and if I click them several times, it results in the page shown not matching the URL bar.

• If I click an anchor link and then press the back button, it does not send me back. (Very annoying when reading READMEs and using table-of-contents links.)

If you disable the JavaScripts provided by GitHub and implement your own instead, then it works better, in my experience.