Network Traffic, File locks and perhaps record locking. Ultimately the best answer is to use a database server to house your data or live with the speed. The only thing you might clean up is record locking in your application. If Network traffic is a problem, then upgrading from say 10Mbs to 100Mbs would help. And of course switches instead of hubs may help. Also dedicating a machine to the database on a network with a switch would also help if the machine hosting is hit with a lot of traffic. Keep in mind all these solutions other than the database server will help but you might not see a decent ROI.