Since the latest update (5.3.1), Rhino is almost unusable because it is so slow. It takes multiple minutes to create a simple solid cylinder. Rebooting is the only solution. MacBook Pro, late 2013, 8 gb, i5, El Capitan. Is anyone else having issues?
I cannot duplicate this as you have described. Can you provide any further details? Please post your Rhino info as detailed here: Reporting problems with Rhino for Mac
I got around it by upgrading my Macbook Pro to Sierra from El Capitan.
It seems better now under Sierra.