Over the past few weeks I’ve used Zoom on a 12" Retina MacBook, an ancient 13" MacBook Air, and, last night, a 27" iMac Retina 5K.
Zoom normally shows a maximum of (IIRC) 20 users at a time in Gallery view, but has an option to increase that 48 at a time. I’ve used that option on both the MacBooks, but on the iMac the option is greyed out, with a message to the effect that the processor isn’t good enough. I find that odd, given the specs of these machines:-
12" : 1.4GHz Intel Co re i7/8GB, Intel HD Graphics 616 1536MB
Air : 1.8GHz Intel Core i5/4GB, Intel HD Graphics 4000 1536MB
iMac: 3.3GHz Intel Core i5/8GB, AMD Radeon R9 M290 2048MB
Moreover, the Zoom screen on the MacBooks is for the most part pin-sharp, being grainy or blurry only as bandwidth and (others’!) camera quality permits, whereas on the iMac the usually brilliant retina screen looks, in Zoom, disappointingly blurry.
None of this seems to make any sense. The iMac and 12" MacBook both have Retina screens, and MacBook Air and the iMac both have Core i5 CPUs, yet both the MacBooks are brilliant for Zoom, whilst the iMac is a huge disappointment. All three machines are configured to display at their “recommended” (which I assume to be their native) screen resolution.
Is anyone able to shed any light on why the 5K iMac, with its renowned screen and graphics, should fail at what even an 8-year-old entry-level MacBook Air with its non-Retina screen does perfectly?