why is the db so slow?

I am running my own database server but I don't have root privilege (and
no hope of getting it.)

I only have 3 tables, with rowcounts of 3000, 48000 and 2 million.
I don't think this is that many rows but most things take a long time to
run. There are a lot of indexes on each table and creating an index on
the 2mil row table takes forever, which I could perhaps live with BUT -

typing something as dumb as \! pwd is not instantaneous either and there
doesn't seem to be anyone else hogging up the CPU.

I am on Linux and due to lack of space in my own account, I have PGDATA
pointing to /tmp.
(This is for a class project to analyze query performance ...I can
recreate the data at any time if necessary.)

Are there any parameters I can set to speed things up?

Thanks
Becky