RX 6800 Phoenixminer mining renders Windows 10 unresponsive?!?

I have just gotten a new XFX 6800 card and wanted to put it to good use, so I downvolted/reduced GPU freq/boosted the ram freq and I hit 63 MH (oh my, for a card like this #eyeroll) right off the bat, but as soon as the card starts mining, Windows become quite unresponsive (dragging a window causes a 1s freeze, etc.) I used to mine with my old RX570 and using the exact same machine + the exact same (three) monitors, the miner didn't slow down Windows AT ALL. But with 6800, mining renders the machine basically useless for normal work, which leaves me completely confused about what could cause such a difference in Windows responsiveness (with that much better a graphic card) and more importantly, how can I fix this? Thank yo in advance