The impact of caching on the system performance or on the user experience
I think that a good starting point to understand how the memory (including caching) works is What Every Programmer Should Know About Memory from U. Drepper. In fact, this is one of the best papers I have ever read about computers.

More recently, I found How misaligning data can increase performance quite entertaining. It is a direct application of the things you can learn from the first one.