The current depth of field implementation is really slow, have artifact, have unpredictable performance.
The goal would be to implement something around the lines of UE4's Depth of field link.
This means having a gather approach for low brightness pixels and a scatter (sprite) approach for higher brightness pixels. Also a background reconstruction pass is described in the presentation.
Primary exploration of the gather approach has been done for the workbench Depth of field.
Estimate : 2 weeks