Every time I make a change in the details of a content-type it takes too long. I though it had to do with the fact that I had too many content-types and fields (~500), but when I load the devel module to see the queries that take that long I see:

Executed 32212 queries in 12267.57 milliseconds. Queries taking longer than 5 ms and queries executed more than once, are highlighted. Page execution time was 55763.32 ms

When I see the details I notice that the vast majority of db calls come from the menu system, e.g.:

1. _menu_route
2. menu_local_tasks
3. admin_menu_link_save

Why is that? Can I avoid some of these? It doesn't seem logical!