Slow Query

My site has been experiencing sporadic spikes in mysql connections, and in the course of investigating, we've discovered a slow query in CommentRSS that is taking typically 45 seconds to execute against a comments table of about 750k rows. A consultant I'm working with has rewritten the query (line 168, commentrss.pages.inc), from this:

$SQL = 'SELECT '. $nidselector .', c.cid, c.subject, c.comment, c.timestamp, c.uid, c.name, c.format, u.name username, n.title FROM {node} n '. $joins .' INNER JOIN {comments} c ON c.nid = n.nid INNER JOIN {users} u ON c.uid = u.uid WHERE '. $where .' n.status = 1 AND c.status = %d ORDER BY c.timestamp DESC';

to this:

$SQL = 'SELECT STRAIGHT_JOIN '. $nidselector .', c.cid, c.subject, c.comment, c.timestamp, c.uid, c.name, c.format, u.name username, n.title FROM {comments} c '. $joins .' INNER JOIN {node} n ON c.nid = n.nid INNER JOIN {users} u ON c.uid = u.uid WHERE '. $where .' n.status = 1 AND c.status = %d ORDER BY c.timestamp DESC';

and then added an index for timestamp and uid. It's reduced the query time to 6 seconds. There may be a better way, but it's improved things on the site considerably for now. Thought I'd report it in case anyone else runs up against such a thing.

Sorry I don't have a patch - still kind of clueless in that area.