restoring a dump with Ubuntu 16.04 using postgres.conf default configuration (autovacuum on) takes several hours, with Ubuntu 14.04 only 20 minutes. Turning autovacuum off in Ubuntu 16.04 makes restoring much faster, with 14.04 autovacuum off has nearly no effect. The PG version does not matter. Same results with PG 9.4/9.5/9.6.
Do you have any idea what could cause this effect (what has changed in Ubuntu 16.04?) and should autovaccum be turned on again after restoring the dump? Does autovaccum slow down other Postgres queries?
Autovacuum should always be on. Is the destination database (the whole db-cluster) new and empty?