only read this because of Niel :-)
Robert Treat
pg_autovacuum requires that the statistics system be enabled and
reporting row level stats. The overhead of the stats system has been
-shown to be significant costly under certain workloads. For instance,
+shown to have a significant cost under certain workloads. For instance,
a tight loop of queries performing "select 1" was found to run nearly
30% slower when stats were enabled. However, in practice, with more
realistic workloads, the stats system overhead is usually nominal.