Have you tested it with regular pg_connects instead of pg_pconnect? while
many people expect pconnects to be faster, often, when they result in the
database having lots of open idle connections, they actually make the
system slower than just using plain connects.
You might want to look into some of the connection pooling options out
there that work with PHP, as persistant connections work well only for a
smaller number of hard working threads, and not so well for a large number
of connections of which only a few are actually hitting the db at the
same time. The becomes especially bad in your situation, where it sounds
like you have multiple databases to connect to, so php is keeping multiple
backends alive for each front end thread.
