Defraggler program is very slow when it comes to large files. Still seems randomly slow to over 100 MB/s on small files. I've seen Windows Defrag use nearly 100% of HDD from time to time of "Active time" according to (Task Manager) even for very large files. Defraggler is at 50% of large, very large video files of an average of 100 KB/s read and 300 KB/s write speed. Drives are in RAID 0 and 128 KB Data stripe size and at SATA 3 at 600 MB/s of 2 TB. Who knows it could be the latest Windows 10 updates.
Windows 10 Pro v1803, Defraggler v2.22.995 (64-bit), Intel RAID.