pg_stat_user_tables
is a fantastic system view that can show us
invaluable information about the tables in our databases and can be
used in diagnosing performance issues. Vacuum statistics like
last_autovacuum
and n_dead_tup
will show if there are tables that
aren’t being vacuumed efficiently and n_tup_hot_upd
if you aren't performing HOT updates.
One of the things to look for first, though, is if there are tables that need new indexes as this can have a significant impact