Okay I'll put it in terms you might more readily understand. Whey you're playing a video game, how long does it take for the computer to recognize you've pressed a button, perform the necessary calculations to interpret what that button press means, and render whatever change necessary to that meaning on the screen?

Electronic throttles, generally speaking respond just fine. They only time when they don't honor the request for acceleration placed by your foot is if the stability or traction control systems decide it's time for them to intervene on your behalf. Now some cars do have crappy electronic throttles (VW/Audi 1.8T cars come to mind), but that's not merely because they have electronic throttles. It's because they have bad electronic throttles. The same can be said of cars with saggy mechanical throttle linkages.