Consult me on how to achive the high perfomance speed on C code.

Dear All,

My code routines taking a time delay issue to generate the output(around 6 sec). I am trying to improve
the speed perfomance to generate the quick output(in nano sec). Can somebody consult me with some tips on
what all the things that should consider in the following code to achive the desired result. I have attached the
code that I am workig on. Kindly reply me with some advices on what are the issues causing delay in my code and how to rectify. 

Thanks you very much