Pausing a Program

Is there a way to pause a running application? I don't want to quit out of it, but I don't want it to hog my cpu either (what it's using it for, I don't know since it's just frozen on a menu screen). I would think that "Activity Monitor" has something for it, but I didn't see anything.

 

It's called HTS (http://www.homevisiontherapy.com/).

Basically, it starts out on a menu screen, and you click a button to begin the session. When the session is complete, it returns to the menu screen, giving you the option to begin again. While on the menu screen, it seems to be doing nothing, yet the CPU is still at 60 (don't know for sure what it means except that the fan is continuously running and doesn't normally).

The reason why I don't want to exit the program is because it only let's you open and close the application a certain number of times before you have to buy another registration code. I would like to get as many sessions in as possible before this.

Thanks for your help!