Agreed, keeping programs (once they've been exited) and data in cache is a good thing as it means that you don't have to read them from disk again in subsequent

Agreed, keeping programs (once they've been exited) and data in cache is a good thing as it means that you don't have to read them from disk again in subsequent runs/accesses. And given that a cache is a mirror of existing data (as opposed to buffers which are temporary storage space), the cache can be instantly flushed by the system if you need that ram for anything else. This means that it's good if the memory resources the operating system needs to function are low, since it then has more memory for caching. This flies in the face of the often heard comment -'it doesn't matter if operating system X is a ram hog, I want my memory to be used'. I also want my memory to be used, but by the applications I run, not the base operating system. If the operating system is lean, the more memory is available to the applications you launch, aswell as the system being able to keep as much data as possible cached to prevent slow disk reads.