C# windows application slows down all other Applications

I have developed a C# windows application in Visual Studio 12. When I run this application, it slows down all other apps and makes PC slow., I think it takes too much of physical memory. Pls suggest some work around to avoid slowing down my PC.

Below is the introduction to application developed : 

The application is very data intensive. The application contains one for loop which loops through around 80000 times and this "for loop" also have one "inner for loop" which loops through 100000 time. I store all the data in lists, arrays and objects(I think these data structures  consuming memory)

 E.X.  for(i=0;i<80000;i++)

         {

              for(j=0; j<10000;j++)

                    { 

                           //do some scientific calculations using mathematical formulas (sine, cos, sqr roots) and calls some user defined functions 

                     } 

         } 

 

Also suggest how to make this application fast!!!