HELP speed up my Postgres

Hi ALL,

	Ive been using postgres for 3 years and now we are having problems with its 
performance.

	Here are some givens..

		We have 260 subscription tables per Database. 
		We have 2 databases.
		
		Our main client has given us 250,000 mobile numbers to deactivate.
		
--
		We we are experiencing
		 91,000 mobile numbers to deactive it took a week to finish for 1 DB only 
the second DB is still in the process of deactivating

	Algorithm to deactivate:
		we loaded all subscription tables names into a table
		we loaded all mobile numbers to deactivate into a table

		SQL:
		update SUBSCRIPTIONTABLE set ACTIVEFLAG='Y' where mobile_num in (select 
mobile_num from LOADED_MOBILE_NUMBERS)

	the script was made is "C"

COFIG FILE:
# This is ARA nmimain

tcpip_socket = true
max_connections = 150
superuser_reserved_connections = 2

port = 5433
shared_buffers = 45600
sort_mem = 40000
max_locks_per_transaction=128

#fsync = true
#wal_sync_method = fsync

#
#       Locale settings
#
# (initialized by initdb -- may be changed)
LC_MESSAGES = 'en_US.UTF-8'
LC_MONETARY = 'en_US.UTF-8'
LC_NUMERIC = 'en_US.UTF-8'
LC_TIME = 'en_US.UTF-8'


.. DB is being vaccumed every week
my box is running on a DUAL Xeon, 15K RPM with 2 G Mem.

that box is running 2 instances of PG DB.



TIA,