As much as I would want adaptivity to be able to cope with such cases in an efficient way and renderers\hardware in general to be able to render that in a blink of an eye too, I think for now, such effects as the bokeh and dof are better (well if not better then certainly faster) done by using post dof generated by z-depth pass for example by using either vfb+'s dof
, which is quite good for the price and what it is capable of, or using by using lenscare plugin
(Alex's Roman's use of it) which is sometimes even better than the rendered dof and bokeh because of one subtle effect it does and other methods\plugins do not do - not sure how it is called correctly but as I remember it is called aerial lens or aerial aberrations or something like that, which occurs on\between the edges of an out of focus objects and produces some nice distortions on objects visible past them which is usually not possible to do by conventional rendering or at least not with the current generation of renderers (correct me if I'm wrong) - this effect might sound like some minor thing until you see the difference on your own renders ) Of course as always glass\almost transparent objects sitting in front of a camera are a problem with post processing method (which is avoidable at least in some cases and to some degree by setting those material to be not visible in masks thus excluding them from generated z-depth pass completely) but the time savings are tremendous even for stills (which I usually do) and I cannot even imagine how much time one could save doing some animations. That's not completely discussion related but I thought it could be useful for someone interested in doing that stuff in an efficient manner ))
edit: Forgot to mention, lenscare's photoshop plugin's implementation is, sadly, almost completely unusable or at least very hard to use and understand, piece of crap - I use it's after effects version in an old version of Fusion which back then could use after effect's plugins - hope someday, they will make some user friendly and logical photoshop version but right now it is such as I described (