Thread Scheduling Model

I just bought Focusrite's Clarett 8PreX Thunderbolt-based audio interface and was having horrible audio performance problems playing back projects in Sonar -- worse than my old Saffire Pro 26 FireWire interface!! At first I thought it was due to the fact that Focusrite's drivers for Windows are supposed to have issues with using a Thunderbolt 2 > 3 adapter. Turns out, after hours of pulling out my hair, it was due to Sonar's "Thread Scheduling Model" setting in the Configuration. I had it set to 2 - Producer/Consumer (which always seemed to work better with my older systems), but all I had to do was change it to 0 (Legacy Spin), and poof!!! Everything is magically working perfectly. I'm running a new Macbook Pro 2016 15" quad-core with Windows 10 via Boot Camp. Does anyone know why this would be? I'm just glad it works and I don't have to switch DAWs!!!!
 
I'm going to plug my old Saffire interface back in and see if 0 - Legacy Spin improves the performance on there as well.