In testing some local image gen software, it takes about 10 seconds to generate a high quality image on my relatively old computer. I have no idea the latency on a current high end computer, but I expect it's probably near instantaneous.

Right now though the software for local generation is horrible. It's a mish-mash of open source stuff with varying compatibility loaded with casually excessive use of vernacular and acronyms. To say nothing of the awkwardness of it mostly being done in python scripts.

But once it gets inevitably cleaned up, I expect people in the future are going to take being able to generate unlimited, near instantaneous images, locally, for free, for granted.