>>The biggest problems with files is that you have to put them somewhere and manage lifetime of them (ie. delete when you're done, which sometimes is not so trivial).
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Exactly, for me, that is the issue. It seems to me the Stream Object takes care of many housekeeping issues for me.

I still kling to the notion however that RAM based storage is more efficient than file-based storage. Look at SQL-Server, as soon as it can, it caches to RAM. Subsequent queries are often orders of magnitude faster than prior queries. Even if in reality, the Stream Object is persisting something to disk, I bet it is doing it more efficiently than I could manually...