Try Linux to see, if issue is in Windows. You can use live-usb and try to measure DPC latency, if you can figure out how to do it on linux, tho you should probably use full installation and install graphic drivers first, you can use dual-boot it is not difficult to set-up... Wdf1000.sys is USB 3, try to disable legacy USB support in BIOS, or XHCI hand-off etc. Disable any USB ports you don't need. Again it may be your other USB devices causing the issue. I think you said that you saw drop after disconnecting some devices. USB audio is the worst! Disable all USB power savings using "Power Plan" app I sent you. Also uncheck turn device off, or allow to wake up computer for all: usb devices like mouse/keyboard and all USB and HID entries in device manager!!! There is still probably a lot of things you didn't try!