Why vectorizing the loop over 64-bit elements does not have performance improvement over large buffers?
This original answer was valid back in 2013. As of 2017 hardware, things have changed enough that both the question and the answer are out-of-date. See the end of this answer for the 2017 update. Original Answer (2013): Because you’re bottlenecked by memory bandwidth. While vectorization and other micro-optimizations can improve the speed of computation, … Read more