It is a LaCie d2 professional with a Seagate IronWolf pro 8tb disk, HDD type CMR. Moving large files to the end of the drive was done fast.
It looks that Defraggler needs a lot of time to find the next small file to optimize. It needs +3 GB but memory is not a problem, CPU is a i7-6950X.
I will try the built in Windows.