With the landing page tab open in Firefox (on Linux), on a 2018 i5 laptop CPU in powersave mode, Firefox keeps the CPU steadily running at around 60% with a few spikes here and there due to the animations on the landing page. I think it's cute that it shows moving clouds and stary sky, but such a hit on performance is not waranted for just a couple visual tricks.
Example page profile for a couple of seconds.