I’m running the latest Linux Mint (20.1 64-bit) and using a Firefox-forked browser.
Scrolling nearly any page on GitHub immediately gives the console error seen in the screenshot below, and then 100% of one CPU core is taken up by the browser process. The CPU core is not relinquished until the browser is closed (closing the tab is not enough).
Someone who knows better than me on the topic suggests “[Web devs] should stop manually repositioning elements with JS upon scrolling because it’s very CPU intensive, and use the CSS keywords for it that have been around for a looooong time.”
Here is the URL in the error message so no one has to re-type it: Scroll-linked effects - Mozilla | MDN
Let me know if I can provide more details.