its not supported at the kernel level because its considered HIGH LEVEL programming. There are so many possible implementation that its easier for MS to simply NOT do it. Whilst people keep harping on about how hard it is I've actually done it... that code snippet .... not a joke. It really IS that easy to do caching.
As I said earlier.. pre-caching is more difficult but only slightly and it STILL doesn't require a game re-write.
In the end it all boils down to this... who here is WORKING with the console and who is guessing ?