Non-real time target

I need a simulink simulation to run on my arduino in non-real time. That is, I have a block diagram model of a physical system that I want to test various inputs on, but I need the results very quickly instead of in real-time.

I've been told (and read) that the default operation for simulink programs to run on a microcontroller is not real-time, however I have done tests and found that my simulations do run in real time.

My question: Is there a way in Simulink to make subsystems in my program to run faster than the rest of the program?

Any help would be greatly appreciated.

Thanks,

-Dan