statistics buffer is full

Hi,

one of our heavy loaded postgresql servers regularly gives

LOG:  statistics buffer is full

Sometimes those messages come when there is a load peak on the server,
so it comes to my mind that it may be possible to improve performance by
tweaking postgresql.conf to get rid of that full buffers.

We run 7.4.1 on Linux 2.4 (Dual Xeon 2,4, 3 GB RAM). pg_autovacuum is
running.

postgresql.conf (tweaked parameters only):

shared_buffers = 20000
sort_mem = 16384
fsync = false
wal_buffers = 256
checkpoint_segments = 6
log_timestamp = true
stats_start_collector = true
stats_row_level = true

Any hints?

Regards,
Bjoern