Mathoverflow page using a lot of CPU

Opening the following page on my browser rises my CPU temperature to over 85ºC (and continues that way as long as the page is open): https://mathoverflow.net/questions/382270/reflection-principle-vs-universes . I am using void linux, and tested this both on firefox and on chromium. My friend using windows also noticed a high amount of CPU usage when visiting that page. What could be the cause of this?