Large NOT IN Statement vs Creating/Populating Temp Table
With a large set you may want to use an NOT EXISTS clause rather than a NOT IN clause.  It will help if you index the id on your feed table.  Using an index will allow the optimizer to use the index rather than reading the table.  Try a query like:

DELETE
FROM    table
WHERE NOT EXISTS (
    SELECT  feed.id
    FROM    feed
    WHERE   feed.id = table.id )