pg_lock_status() performance

I have a unloaded development server running 8.4b1 that is returning
from a 'select * from pg_locks' in around 5 ms. While the time itself
is not a big deal, I was curious and tested querying locks on a fairly
busy (200-500 tps sustained) running 8.2 on inferior hardware. This
returned (after an initial slower time) in well under 1 ms most of the
time. Is this noteworthy? What factors slow down best case
pg_lock_status() performance?

edit: I bet it's the max_locks_per_transaction parameter. I really
cranked it on the dev box during an experiment, to 16384.
testing...yup that's it. Are there any negative performance
side-effects that could result from (perhaps overly) cranked
max_locks_per_transaction?

merlin