pg_dump and pg_restore

Hello all,
I was testing how much time a pg_dump backup would take to get restored.
Initially, I tried it with psql (on a backup taken with pg_dumpall). It
took me about one hour. I felt that I should target for a recovery time of
15 minutes to half an hour. So I went through the blogs/documentation etc
and switched to pg_dump and pg_restore. I tested only the database with
the maximum volume of data (about 1.5 GB). With
pg_restore -U postgres -v -d PROFICIENT --clean -Fc proficient.dmp
it took about 45 minutes. I tried it with
pg_restore -U postgres -j8 -v -d PROFICIENT --clean -Fc proficient.dmp
Not much improvement there either. Have I missed something or 1.5 GB data
on a machine with the following configuration will take about 45 minutes?
There is nothing else running on the machine consuming memory or CPU. Out
of 300 odd tables, about 10 tables have millions of records, rest are all
having a few thousand records at most.

Here are the specs ( a pc class machine)-

PostgreSQL 8.4.3 on i686-pc-linux-gnu
CentOS release 5.2
Intel(R) Pentium(R) D CPU 2.80GHz
2 GB RAM
Storage is local disk.

Postgresql parameters (what I felt are relevant) -
max_connections = 100
shared_buffers = 64MB
work_mem = 16MB
maintenance_work_mem = 16MB
synchronous_commit on

Thank you for any suggestions.
Jayadevan

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