In vMix v12, I built a set of Desktop Capture inputs with source "localhost". Back then, vMix Desktop Capture app was required, although I was capturing from a second screen on the same PC.

On v14, without running vMix Desktop Capture app, I changed the inputs to have source "My Computer". This is apparently not the same as "localhost", because suddenly my render time went from < 30ms to > 200ms.

I'm going to try testing with source "localhost" to see if I can find a configuration that doesn't impact render time but allows capture from the local PC without vMix Desktop Capture app running.