SSDs don’t suffer from access latency due to fragmentation like spinning disks do. In fact, one would probably be better off not defragmenting an SSD because all those writes will reduce the life of the disk.
Nope...OK, lets look at APFS here instead of HFS+..
Here's what I'm finding out today.. APFS understands which files will give the biggest performance boost once defragged. It works in the background when the machine is idle, so defrag won't impact system performance.
For macOS, High Sierra automatically converts the system drive to APFS as part of the installation process. The process does not move your file data. It does copy and reformat file system metadata, but does not erase the old metadata until the rewritten metadata has checked out. The metadata provides information about other data and I believe this is where the problem is. Apple will fix it, just a matter of time. For me a re-format did the job..
Why can my buddy buy a new Macbook formatted for APFS loaded from Apple with High Sierra and it runs perfect? Now take that same Macbook and install the HS update on a non APFS drive and re format to APFS and it runs like chit? Not my opinion but just what I'm seeing on other forums.. There is a serious flaw in the live update of the file system causing everyone problems..
I cured my problems completely simply by re-formatting the drive with Disk Utility APFS and re-installing the same data and using first aid.. I'm very happy with the results..
