The rendering of DOF in Vue is slow - but i only see it as something that is included, that it can be used. Sure a DOF effect can be added with just about any good Paint program, doesn't have to be Photoshop.

But if you want full control of the DOF areas and really want to have an exact distance or area to have a sharp or unsharp look, than you let it calculate in Vue - takes long, but the effect will be calculated more realistic - sure most of times, the exact realstic look isn't needed, as the human eye and brain can be tricked easily, to take pretty anything for real (or unreal), as long as it's following simple basic rules ...

If you want to, take a look at my blog site for a little tutorial, how to setup and use the DOF function - and if you want to have a 'non' grainy DOF render in Vue , you should use the Hybrid v.2.5 method (like Bruno and Rutra already mentioned) with about three render passes, instead of the raytracing method.

arraxxon.blogspot.com/

All that quickly described in my small tutorial ... the effect should be nice smooth and not grainy ...