So I've seen other posts here that do discuss this, but I'm not quite sure how the time complexity (I think?) relates to the actual number of floating point operations done per second when you're changing the size of the matrix you're working on. The time taken is of course the same each time, since it is padded to a size $N(>n)$ which is a power of 2. So the number of floating point operations is also according to the new dimension $N$, right?
So for example, what's mentioned in this answer and the other answers there wouldn't exactly be the same for the actual number of floating point operations, right? Since all the zeros added at the beginning would be used in the computations anyway?
As I'm doing this right now, my, say 450 sized matrix multiplication takes about the same time as the 512 one, but that's expected. When calculating the floating point operations, they would be according to the larger N, right?