You need to adjust your driver settings. In Reason, go to edit>preferences>audio. There should be a pulldown menu with a few different driver choices. ASIO is usually the best choice in there for Reason, but you can try the others and see how they work. There's a slider in that tab that says Buffer size. Slide that thing to the left to make the buffer time shorter. I find 10 ms to be somewhat acceptable, 5-7 close to unnoticeable delay.
If you make it too short, you'll get crackles and pops. A faster computer and better soundcard will allow faster latencies.
I run my audigy at around 8 ms in Reason 3.0 with the creative ASIO drivers.