I need help in asking the right questions

For years my software has run quickly on a local drive but when there are 
large files on network drives, it slows down terribly when moving from 
record to record.

I am going to approach our IT department about, but before I do, I need to

know what questions to ask.

My software is in a large hospital, but at this point it runs stand alone 
(not netowkred) using Paradox 10 Runtime. I think they use Novel network
What are the factors which will slow down performance when a database runs

on a network drive?
I don't know where to start. I would like to get information, bring it
back 
to this forum and ask for help in sorting this out. Has anyone else run
into 
this problem?

Thanks in advance

Craig