There are some cases where corona may perform slightly faster than Vray, but there definitely are not any cases where Vray can not be optimized to perform reasonably well.
Thanks for this brilliantly worded quote.
Unless we have the right tools finished there is imho no point in comparing/ranting with vray. I love corona - but without adaptivity and some more complex features it's (yet) not something I can actually use in production, at least not if i want to do animation and realistic render times.
There are some cases where corona can play out its strengths (unbiased methods) where Vrays biased stuff just fails - but this is just a tiny percentage of daily work. What I learned from the year of using corona is that it's a lovely tool to work with but it's still taking way too much time to get clean images - way longer than 95% of Vray renderings - which is also due to the fact that it's not adaptive.