Odd issue with NIC settings and SQL-backed application

Here's an interesting one. Hoping someone may have some ideas.

We have Unifi 48-750w switches. The PCs are all home runs, though half go through a PoE phone. We have a SQL-backed application that we run extensively on all workstations. SQL Server 2017 on Win Server 2016, 96GB RAM, 14 cores, SSDs, seems to be sufficient for the load. There was a noticeable difference when upgrading to Windows 10 on the workstations. The difference was noticed on both PCs upgraded to 10 and brand new PCs that came with 10.

After a significant amount of research and trial & error, I narrowed it down to NIC settings. Going through the Advanced options in device manager on the NIC, and disabling everything in there makes a significant difference in the speed of the application. NICs mostly have recent firmware, especially the brand new ones. Firmware updates haven't seemed to make a difference. I haven't had time to go through all of the different settings to narrow down if it's a specific one yet, requires user testing between each change. Any thoughts? Thanks!