Client/Server Fujitsu Cobol applications

Hi!
I've an application installed in the server (2003 server; 1GB RAM) and
in the clients I've installed the runtime of Fujitsu on PC's with XP up to
40 PC's. We shared a folder with our application (with our cobol database
files) in the server.
I'm having some problems, because sometimes when I run a module of my
application it takes 30 seconds and sometimes it takes more then 5 minutes.
Do you know any similar situations, or why this is happening??
Do you know a better way to configure this "Client/Server" application?


Thanks
JM