I'd have to see the data / where you're at so far / the usage case to be sure, but honestly dropdown menus are -- and have been for decades -- really garbage from a UX perspective. This is only exacerbated by multi-depth (nested) dropdowns when it comes to on-screen navigation.

To that end, I've slowly been shifting to turning such "complex" menus into modal dialogs.

Menus on a lot of sites are getting so big, they're banging heads with what in the military is called "information overload". I call this on websites "link overload" where you end up shoving too many links at users at once, or make them hunt through too many menus to try and find things.