Help needed on performance

If there's a good FAQ on this, please just point me there....
 
Background
------------
I have a database that has 3 tables in it. One of the tables has about
15-20 fields in it, a number of them are strings, and so I have defined
them as TEXT. The others are mostly INT4.
I have indexes on 4 of the TEXT fields, and on one other INT4 fields. 
 
The table has 500k to 1m (size fluxuates) rows in it and is run on a
Dual Processor 2.4 Xenon, with 2GB of RAM and a single IDE drive. Its
running RH8, and has Apache running as well as Postgresql.

 
 
Problem
----------
The crux of the problem is performance. At somewhere around 500k
records in the table, the speed of SELECTs and DELETEs gets really poor.
'Poor' as in 2-3 minutes to do a DELETE of 1k rows. Under this number,
the speed is excellent.
 
Any ideas on this?
 
TIA,
 
 
 
Dave Strickler 
MailWise, LLC
(617) 848-5942
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