\d very, very, very slow

I'm seeing very, very slow response to \d <tablename> - around 15-20
seconds on an otherwise idle Netra.

PostgreSQL 7.2.1 on sparc-sun-solaris2.8, compiled by cc -xarch=v9 -Xa

Running psql -E shows that \d is issuing 4 queries. Picking one at
random at running it through explain analyze shows three nested
seqscans and a few joins, taking 6500ms.

(Running the same query on a Linux box running Postgresql 7.2 with the
 same schema and similar postgresql.conf  shows the same query plan,
 taking 80ms.)

So is 15-20 seconds for \d unusual? If so, where should I start looking
to see what's broken?

Any thoughts appreciated.

Cheers,
  Steve