Here's an explanation of what APFS is doing to make file copying to the same volume almost instantaneous: http://dtrace.org/blogs/ahl/2016/06/19/apfs-part3/ ht

Here's an explanation of what APFS is doing to make file copying to the same volume almost instantaneous: http://dtrace.org/blogs/ahl/2016/06/19/apfs-part3/ http://dtrace.org/blogs/ahl/2016/06/19/apfs-part3/ The Mac App Store reviews on the disk speed test tool they are using are abysmal, so I wonder if it's truly testing the disk performance or being fooled by the tricks that APFS is doing.