I am currently subscribed to 32 feeds. Some feeds contains more than 1000 items, many contains more than 500 items.
When examine it under Task Manager, it consumes 50Megs of RAM.
It is pretty fast though.
Also support for OPML files and RSS, RDF and ATOM. And archiving capabilities...
The thing is I wrote it in Delphi 7 and looking for some support.