i had a slave that was lagging by 2~5mn.. slowly but surely, without
high load coming from the read request.
overall... the average load was good. (around ~4 on an octocore).

After many try i found that : vacuum analyze pg_listener; instantly
solved the problem.
(recovering from a 2mn lag in just a few second, and now synched with ~3s lag).

Any tought about why i could have a bloated pg_listener ?

postgresql 8.3.6
Slony 1.2.15
pgbouncer

-- 
Laurent "ker2x" Laborde
Sysadmin & DBA at http://www.over-blog.com/