It's good to see this get some attention. I spent a long time trying to figure out how to make full screen zoom usable with an external display. I found if you

It's good to see this get some attention. I spent a long time trying to figure out how to make full screen zoom usable with an external display. I found if you enable the "Increase Contrast" accessibility feature, performance is improved, but it does negatively affect aesthetics. I answered my own question about this on Apple StackExchange here: http://apple.stackexchange.com/a/157118/70049 http://apple.stackexchange.com/a/157118/70049