I recently committed the following change to the Development Version of FeedWordPress:
Memory usage / Reduce the number of SyndicatedLink objects we are loading up with every pageload, on updates, etc. SIDE EFFECT: feedwordpress_update_feeds filters must be revised to work with an array of numeric IDs, not an array of SyndicatedLink objects
This change will be part of the next public release of FeedWordPress. Interested? Curious? You can check out the details at the WordPress plugin repository ...