I assume you use irradiance cache in Vray... and of course irradiance cache will be always faster than path tracing. Once corona has irradiance cache, rendertimes in such scene could get significantly faster.
For starters, i would try to create new scene with defaults... there is no need to have max. sample intensity at 40.
Going around the render settings and randomly changing things is not going to help you much.
Still, for how simple the scene is, and how fast your machine is... there seems to be a bit more noise than it should...