Case in point: a simple example of code which copies 1MB of data with SSE and slows down on misalignment: https://news.ycombinator.com/item?id=12718625 https:/

Case in point: a simple example of code which copies 1MB of data with SSE and slows down on misalignment: https://news.ycombinator.com/item?id=12718625 https://news.ycombinator.com/item?id=12718625 Presumably due to the hairball of cache implications, as you put it. But it also is true that the choice of aligned/unaligned instructions makes no difference if the array is aligned.