You need a fairly modern laptop to change the screen refresh rate like you're describing. Older laptops do 60Hz (or whatever) refreshes at all times, they can't change refresh rates like that. The compositor should only paint relevant pixels on the screen.

I'm sure that some spinners are horrible and peg the CPU, but unless your machine is older than ~2018 there is something wrong with your setup if spinners (and not intense operations behind them) cause your battery to suffer.