As memory is license free, it makes sense to invest here to use your CPU more efficiently. In OLTP databases the buffer cache has a prominent role when it comes to memory consumption.
However, a number of questions arises. How well is your buffer cache set up? Are there any I/O bottlenecks in your database? Can you trust the buffer cache adviser to lead you to the optimal solution? What objects should you put in the keep cache?
We will try to answer these questions by focusing on tables that do not fall into either or these categories: They are cached all the time or they are ageing out very soon.