I noticed wildly inconsistent GPU render times on a scene that I am working on.
The CPU (i7 860) render time is 1:12.
Switching to GPU (GTX 750ti with 2GB RAM) the time is 0:34 with 1.6GB used. If I immediately render again without switching to the 3D View, the render times become progressively slower: 1:04, 1:19, 1:21
If I switch back to the 3D View and re-render, the time returns to 0:34.
The CPU render times do not change from render to render.
NVidia Driver 340.52
Any ideas of what could be causing this before I try rolling back my video driver?