Necroing thread, sorry bout that.
While doing some game prototyping I got annoyed about this again so I tried a few solutions.
What worked was to explicitly set the max framerate in the GPU driver. No need to add "prefer performance", at least for me.
I just set it to 60 and I got my debugger back to normal.
(this is on a pre-Harman SDK btw, but I doubt that changes anything).