That's odd - I tried the same page, and felt it was very responsive, up until I did 7+ square root operations. This is in Vivaldi, on a Windows 10 (2.5 year old fairly beefy "gaming") laptop, with a bunch of tabs and Spotify running. I do have uBlock Origin enabled, though even with it disabled that page seems fine to me.

Not defending or excusing it, or doubting your results - I guess mostly lamenting we don't have more consistent performance across platforms...