I got around to testing this link on my laptop, but for me it does keep my CPU between 25% and 30%.
I am on Firefox version 76.01 with no active add-ons for the PC-gamer site, if that makes a difference.
I do have Ublock Origin and one that is called "Dark background and light text" but both are disabled for this site. I will try testing it on my work laptop tomorrow and see if there is any difference for me.