Fixed size shift register

Hi all

I am making a time critical labview code and trying to optimise it to the maximum extend possible. There are cases in which i need to buffer say around 50 elements and then analyse the pattern. I use shift registers for these. But they buffer all the values, from the start, where as i need only past 50 elements. I think, my code will run faster if this problem is solved. Is there any efficient method to store only the past n number of elements?

Thanks

Arya