Still takes time to render, bit quicker than V5, though I haven't done any proper tests yet.
However, there is now a huge selection of MB presets to use which is pretty cool, not sure exactly how many, got to be close to 50!?!
I have used them before, but because of the render times (which is shame as the MB stuff can look really nice) I tend to try and use the native color correction and filter tools in Vegas .