Grass is the single most taxing thing there is, and stretching it further than default won't help it either. Also, didn't you boost requests-per-frame?
If it's about inconsistent frame rate, I guess the problem is in the generator. Roads currently sometimes cause syncs on the GPU, caused when one road has to be flushed before the other can be processed for programmatic blending. Currently it's flushed after each road, regardless of whether the road segments intersect or not. With many roads in one place it may cause a non-optimal GPU utilization, which may be more prominent with high requests-per-frame values. Note this only affect stuttering when moving, when many new tiles have to be generated. Obviously it will have to be optimized, along with other things in the road system, but it's something I'm postponing until the road system upgrade.
However, the changes that Oculus brought in with DK2 leave us with mixed feelings. Expecting that anything other than simple demos will be able to reach consistent 75 or later even 90 fps in stereoscopic rendering mode is kind of crazy. Things like portrait displays requiring locked vsync make it hard. I hope they manage to get a low persistency freesync panel instead; the whole vsync thing is a bad heritage from CRT monitors anyway and should have been eradicated a long time ago.