As long as you do not have algorithmic dependence within the data in a cache line, you can regard calculation on that data as a constant that is dependent on the size of the data in the cache line. Even more so if you can utilize SIMD instructions. I know what I wrote wasn't clear on this, I was writing it in a hurry, sorry about that.

The reason I talk in cache lines, is because it's taking the real world aspect into the analysis of the algorithm. A theoretical analysis, while valuable in some aspects, are very far from the real world scenarios. I have done countless theoretical analysis of algorithms, found the actual (hidden) constants in big-O ect. but it just doesn't model the real world very well. This is the exact reason you see many fast algorithms use a naive, but cache friendly algorithm once the input is sufficiently small (e.g. with a divide and conquer algorithm).