A lot of things which affect performance can be changed within CQ (without major configuration or even coding just by adjusting the things you want to get displayed or used.
If you’re looking for some performance on your authoring systems, you may consider to disable some information, which is permanently shown to the authors. One of these pieces of information are the number of items in the inbox. This will create every once in a while a background query which slows down your system. It’s essentially the same query which is executed when you open the “Inbox” Tab.
If you’re not using this feature very often, you should disable it for your authors (or at least for the ones who don’t use it).
Open the user settings of the author and un-ceck “Inbox”. If you don’t use notifications, uncheck them too. This will leave you only the link to the impersonation feature which isn’t expensive in terms of rendering perfomancee, but often very useful.