INSERT performance

I'm running PostgreSQL 7.3.4 on Windows 2000/Cygwin (AMD Athlon XP+
1800, 512MB RAM).

I want to insert about 500 records into a table. The table is heavily
indexed (has about 10-12 indices created on it). The insert is performed
in a transaction block.

If I keep the indices on the table, the insert takes about 12 seconds.
If I drop the indices, do the insert, and then re-create the indices,
the entire process takes about 3-4 seconds.

I am somewhat surprised at both of those performance numbers above -- I
would have expected both of them to be a lot smaller (about half of what
they are). 500 records is not that big of a number! In particular, the
transacted insert without indices should be very fast!

Are these numbers about in range to what I should expect from
PostgreSQL? I looked through the various performance FAQs and I cannot
use the COPY command since the data needs to be processed first, and
this can only be done in memory.

Any suggestions/pointers would be much appreciated.

Thanks,

Razvan.