Diaphragm Depth Of Field optimization

Hey there

I was wondering if anyone could provide some tips on optimizing the new Cinematic Depth of Field. The visual results are fantastic, but we’re currently receiving a hit of almost 2 ms for Diapghragm DOF whenever we use it, even with a wide focal plane. Is this to be expected? Attached is a profile image.

I’ve searched and online and can’t find much information on optimizing it. I don’t mind paying the price on a shallow dof cinematic shot, but it’s unclear how to tone down the cost on a case by case basis without switching to the less cinematic depth of field options.

Thanks in advance