Go through this check list:
1, The hard drive is very important on the server. Try doing a defrag.
2, The network is important on multi-station setups. Do they have a good router? They are very cheap.
3, Firewall and security software can slow things down more than anything. Make sure the POS.exe program (ezPower) has full access privileges with any security software. Otherwise, every file access can be checked and slowed down. This has become more common in recent years.
4, Version 13 is limited but there are some tools you can use. Open the Tools / View Optimize Points. You can use the Clean button. Also, look at the unpaid/open records. If you have open records from early years that requires a lot more work for the software. Closing up open sales records can help.