Can someone please help me out with renicing excel?

I've tried to search Google for a good command line description of exacly what to type, but I can't find anything.

Excel runs fine for me when I have small programs, sheets, or charts, but I've been trying to run calculations for over 31,000 values and it is running terribly slow. I ran the same calculations on a much slower PC and they ran in less than 5 seconds. My brand new macbook with 2.4Ghz processor and 4GB ram takes minutes. It sucks. So, I want to reprioritize excel with the hopes that it will run faster.

Or if anyone has any other suggestions please let me know. Thanks.