Did a test today, cloned Windows from SSD SATA (500MB/s) to SSD PCIE (the 1500MB/s one), note if you do this you need to remove all localmachine/system/mounteddevices from the registry or it won't work.
Booted Windows off new PCIE SSD and same load speed... very interesting. Changed swap from 1500MB/s SSD to 3000MB/s SSD and no change. Changed swap file from Windows managed 10G to 100G and no difference in Windows load speed either.
Haven't got time to test and play with DCS today :(