Where is the best place to store a Wordpress multi-level menu?

Question

caching

The site has a tree-like menu that contains three steps: Category A...n -> Subcategory 1...n -> Post 1...
n each of which is more than ten posts, then building this whole menu, as long as a snake, takes quite a lot of resources. In this case, the menu is displayed both on the category pages and on the posts pages.
What is the best way to get rid of menu building on the fly?
(Menu can only change if subcategories or posts are added/removed)

Answer 1

Drive into transient cache