Even by today’s standards, V-Ray 3.00.03 packs a formidable set of tools:

Cause: Hardware driver incompatibility or low GPU memory for VFB.
Fix:

The rendering engine itself received optimizations for speed. The update introduced a more efficient Embree ray-tracing engine implementation, which significantly reduced render times, especially for scenes with motion blur and displacement.

Enable Embree (under System > Raycaster). It accelerates ray intersection by 15–30% on multicore CPUs.