In preparation for a new release of my news reader, I have implemented categories support in the DB, and rewritten the Python feeds loader to use threads, and to clean up old news items.
The threaded feeds loader is more than 10x faster than the old one (obviously it depends on the number of feeds), and seems to perform well. If you feel adventurous, you can try it now. To use it, you also need the updated SQL schema in preparation for categories and the corresponding feed management page.
The next release will feature an optional frames-based interface, categories, search, and OPML export/import. It will take some time though, what with work and vacations coming up. Let me know if you have any features you would like to see implemented.