Why use shared cache?
There is no more efficient way to increase the scalable performance of applications then the use caching to unload deeper layers.
>> Shared Cache>> Shared Cache Server>> Service Cleanup>> LFU
Cleanup Strategy - LFU
Least Frequently Used: Means the object's witch are used less will be deleted from the cache / if all objects are used in same frequency the objects will be used in a randomized order
Cleanup Overview can be found here.