Sharing Dos App NT 40 Workstation Slow

I am sharing a DOS base application on NT 4.0 workstation. Initially the application was working fine. This workstation also shares 4 printers via network print servers. The application just slowed down for no reason that I can think of, except too many shares on one workstation. After the application loads switching between modules use to be a snap, now it takes 3x as long, but once there scrolling through the records is a breeze. All database records not needed has been purge. Each useropens about 30 files when connected to the application, there is not more than 5 users connected at any one time. I have set the number of open files and buffers to max, still no help. Network is 10/100 autosensing. What else can I do? If I move the application to a NT server would that fix problem completely. Frankly I think it is time to can the DOS application and move to a more conventional windows base program.