Feed forward subsystem help

Hi folks. I have an idea for a control strategy, but I am having trouble implementing it using Matlab/Simulink. I would greatly appreciate anyone's help!

The idea is to have 2 systems running: One is the main, physical system simulation, and the other is the "peek ahead" simulation. The "peek ahead" simulation is the same as the main simulation, except it runs much faster to show me what will happen to my physical system simulation if I apply a certain input.

The point is to test out inputs on my "peek ahead" simulation, see the response, and use some basic logic to feed forward inputs into my running simulation BASED ON the results of the "peek ahead" simulation. The kicker is this: I need my "peek ahead" simulation to be running much faster than my main simulation so that it can actually be of use.

My question: How can I run a subsystem at a faster rate of time than the main system?

Again I would really appreciate any help!