Indeed, but the OP specificly mentioned DCSW 1.5, which is already updated to runtime 1.3 ;)
With the DK2 I tend to use original resolution and mixing high/medium settings, and in 1.5.3 the framerates are more than enjoyable, not manage to get 75 all the time though, but nevertheless the 1.3 runtime is way way better than 0.8.0.0 was before.
Also make sure you have the (in case you are on the green side) latest Nvidia drivers, which already have the VR support.