I had the problem that navigating the page in firefox almost set fire to my CPU on my 2yr old linux dev laptop. Really liked the visualisations, though.
navigating the page in firefox on my 2 year old Mac M1, with about 50 tabs open and a few other applications running including Krita, Chrome, VS Studio, The Terminal, Preview and a couple finder windows gave no problems whatsoever, so maybe they should look at it but not high priority.