I am trying to add a drop shadow to views that are layered on top of one another, the views collapse allowing content in other views to be seen, in this vein i want to keep
So yes, you should prefer the shadowPath property for performance, but also: From the header file of CALayer.shadowPath
Specifying the path explicitly using this property will usually * improve rendering performance, as will sharing the same path * reference across multiple layers
A lesser known trick is sharing the same reference across multiple layers. Of course they have to use the same shape, but this is common with table/collection view cells.
I don't know why it gets faster if you share instances, i'm guessing it caches the rendering of the shadow and can reuse it for other instances in the view. I wonder if this is even faster with