You could use methods like the do in web development where the menu could have a hard reference to a very simple file like a shape of the menu and size but a single color in the meantime load the proper texture asynchronously and swap it once it’s done.
Something like this: (it’s an external link)
You temp images could be very lightweight and hence load nearly instantly.
An older epic talk on the asset manager:
This is a pretty extensive video regarding the asset manager that is rather easy to follow:
