autovacuum, any log?

Hello, I have a postgres 9.0.2 installation.

Every works fine, but in some hours of day I got several timeout in my application (my application wait X seconds before throw a timeout).

Normally hours are not of intensive use, so I think that the autovacuum could be the problem.

Is threre any log where autovacuum write information about it self like “duration for each table” or any other relevante information.

Another inline question, should I exclude bigger tables from autovacuum or there are some mechanism to tell autovacuum to not run often on bigger tables (tables with more than 400 millions of rows)

Thanks!