I've noticed I have some scenes where, when I click something to select it, there is a delay during which the menus flash multiple times, which suggests the interface is being refreshed multiple times. It isn't as bad as described by the original poster (for example I don't see any delay in the library), but something is not being done right and it makes things less responsive. Tried rebuilding the index, updating graphics drivers, fixing any invalid materials, but no difference.

On the other hand, some other scenes don't have those issues.