Disable vacuum delay, as discussed on hackers.

src/backend/utils/misc/guc.c

@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.228 2004/08/07 03:08:44 wieck Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.229 2004/08/08 15:37:06 momjian Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -1046,7 +1046,7 @@ static struct config_int ConfigureNamesInt[] =
 			NULL
 		},
 		&VacuumCostDelay,
-		50, 0, 1000, NULL, NULL
+		0, 0, 1000, NULL, NULL
 	},
 
 	{

src/backend/utils/misc/postgresql.conf.sample

@@ -74,7 +74,7 @@
 #vacuum_cost_page_miss = 10	# 0-10000 credits
 #vacuum_cost_page_dirty = 20	# 0-10000 credits
 #vacuum_cost_limit = 200	# 0-10000 credits
-#vacuum_cost_delay = 50		# 0-1000 milliseconds
+#vacuum_cost_delay = 0		# 0-1000 milliseconds
 
 # - Background writer -
 #bgwriter_delay = 200		# 10-5000 milliseconds