I have 65℃ and 80% utilization. GTX 1660ti. If your utilization is not also higher than mine, you may have a cooling problem.

The main menu is pretty busy. There are swaying trees, a fire, particle effects, lighting effects, etc. However, a person generally clicks through the opening menus pretty fast, so you wouldn't save much power if the animation was turned off.

I'm for greening every menu when it wouldn't detract from the ambiance of the game. Especially if you're playing on a laptop, but if you're plugged into power it's power you or somebody has to pay for.

I'm not just talking about Valheim, of course. All devs should get creative and ask, every time, "Does this menu/dialog need to be animated?" You can do a lot with a sepia-toned still image, or a picture of a rune-stone, etc.

A menu should not become an industry-standard performance benchmark, as in "Hey, I can run the Valheim main menu at 60fps!" "You lie!"