After upgrading to Windows 10 over 7, it takes about 20 seconds just for AmiBroker to load the database from a file shared drive on Windows 10 server. 7 loaded it in under 5 seconds. Here's the fix: https://www.zubairalexander.com/blog/how-to-fix-slow-access-to-network-shares/
I also resetted the TCP/IP and Winsock stack (both on workstation and server).
You should be using local hard disk the fastest you can get. Disks are already slowest component of any computer orders of magnitude slower than RAM. Adding huge network layer latency to the equation is simply big no-no.
The above fix I mentioned or other SMB tweaks or TCP tweaks did not actually succeed in resolving the slow database loading issue.
What actually did?
Turning off IPv6 on the workstation. The database now loads in a more normal three seconds instead of a variable 12-30 seconds.
Very useful step-by-step: https://www.sysprobs.com/windows-7-network-slow
The first fix (prefer IPv4) in the below allows IPv6 to be turned on again without slowing down the file sharing: