Need to tune for Heavy Write

Dear all,

From the last few days, I researched a lot on Postgresql Performance
Tuning due to slow speed of my server.
My application selects data from mysql database about 100000 rows ,
process it & insert into postgres 2 tables by making about 45 connections.

I set my postgresql parameters in postgresql.conf as below: ( OS :
Ubuntu, RAM : 16 GB, Postgres : 8.4.2 )

max_connections = 80
shared_buffers = 2048MB
work_mem = 32MB
maintenance_work_mem = 512MB
fsync=off
full_page_writes=off
synchronous_commit=off
checkpoint_segments = 32
checkpoint_completion_target = 0.7
effective_cache_size = 4096MB

After this I change my pg_xlog directory to a separate directory other
than data directory by symlinking.

By Application issue insert statements through postgresql connections only.

Please let me know if I missing any other important configuration.

Thanks