I'd like to see a term that emphasizes that what web developers consider real time is "so fast it looks instant to humans," rather than guaranteed low latency that another system can rely on (or whatever you consider the true definition of "real time" to be).

So maybe something like "blink speed." (Then we'd have blink speed apps on retina displays.)

Low-latency seems kinda descriptive if I have understood the 'real-time web' concept correctly.

I've heard "auto-synchronizing" suggested, but I think that's probably too wordy to catch on. How about "immediate"?