Pre-creating partitions incurs insert penalty

I noticed a very strange performance issue after I pre-create daily
partitions for the next month on a table that has a very large insert volume
(30 million a day). After the partitions are created..the inserts seem to
slow down. I verifiied that this was the issue by dropping the
partitions...When I dropped the pre-created partitions..the performance
issue disappeared. Looks like you cannot have too many partitions (in this
case..I had a total of 35 partitions when the performance issue was noticed)

Postgres version is 8.1.9 on a 8 core Red Hat linux box with a Raid 10
configured hard frive set up that has 6 15K disks . The load factor on the
box is very low ..just the insert performance suffers after the partition
creation.