Almost certainly. In real time, the brain is processing all incoming stimulus. In a dream/imagined scenario, you are only processing as much as you your brain

Almost certainly. In real time, the brain is processing all incoming stimulus. In a dream/imagined scenario, you are only processing as much as you your brain is pushing into the scenario. Your not collecting millions of photons via your eye and interpreting a ball as green, your brain just says "green ball" and moves on, allowing for much faster replays/dreams than real-world experience.