KC,
Assuming that you are on versions 8 or 9, there are a number of things that you can do within Great Plains to increase performance.
1) Check the setting for the auto-complete fields under user preferences. The default is to save 10,000 entries FOR EACH FIELD, forever (the zero means nothing ever gets removed until you reach the 10,000 entry mark). This will eventually bring any normal system to its knees when you open a window that has autocomplete fields. We usually suggest a more realistic number like 10 or so, and have unused entries removed weekly.
2) By default, the homepage is set to refresh every hour. Assuming that most everyone logs into GP at about the same time every day, the server will be extremely busy refreshing all of the homepages around the same time each hour. We usually recommend turning off the homepage or at least stopping the automatic refresh. By the way, Outlook on the homepage can sometimes cause issues as well.
3) When Great Plains is installed, there are jobs created in SQL Server, one per company database, called Remove Pjournals. These jobs are supposed to run every half hour and will remove temporary information about entries that are fully posted. These jobs do not run unless someone goes into SQL, finds them, changes a setting and applies the change, and then goes back into the job and resets it to its original settings and applies again. The idea is that the act of applying the changes will actually enable the jobs. In a busy location, these tables will quickly fill with thousands of entries that are not needed once entries are actually posted.
4) A well set up SQL Server maintenance plan for each of the company databases will go a long way towards making GP perform well. You can also create backups of both the database itself, as well as the log files, so that the logs do not continue to grow until you run out of disk space.
5) Although this is slowly changing, Great Plains was originally designed to farm out most of the actual processing to the workstations. Make sure that your network infrastructure is clean and efficient as a fair amount of data travels to and from each workstation continually.
It's been a while since I set up a new system from scratch so I will have to check my notes to see if there is anything else to suggest. Hope this helps and good luck.
LyleU