Probably very little if it is built on top of CoreAnimation, since that set of OS APIs is extremely heavily optimized specifically to enable animation-rich UIs that are light in terms of CPU and battery use.
https://arstechnica.com/gadgets/2007/10/mac-os-x-10-5/8/
Of note:
> [The] advent of Core Animation probably means that we'll have to endure some amount of gratuitously animated software created by "overly enthusiastic" developers. But the same was true during the introduction of styled text and color graphics. Mac developers learn quickly, and Mac users are good at rewarding restraint and punishing excess.
There’s a similar story around SwiftUI. It was initially created by the Apple Watch team at Apple, then extended to all the other OSes (all this was long before it was made public).