I see people downvoting this. Anyone who disagrees with this, we have YAGNI for a reason - if someone said to me my performance was fine and they added caches, I would look at them with a big hairy eyeball because we already know cache invalidation is a PITA, that correctness issues are easy to create, and now you have the performance of two different systems to manage.

Amazon actually moved away from caches for some parts of its system because consistent behavior is a feature, because what happens if your cache has problems and the interaction between that and your normal thing is slow? What if your cache has some bugs or edge case behavior? If you don't need it you are just doing a bunch of extra work to make sure things are in sync.