How do I run a program on someone else's terminal in a fair manner?

I wish to run a very heavy python script which gobbles up a lot of CPU on someone else's terminal I have access to开发者_如何转开发. This other user logs infrequently on his terminal. I want the program to not take too much CPU resources when the user is logged in. If not then the script should run freely. Is there a UNIX command to accomplish this?

Be nice :-)