Solution:
Just add “Icedrive.exe” to excluded processes in Windows Security.
Results:
It is reducing disk usage from 100% (or 5 minutes straight on HHD to 0-2%.
It also make faster starting sync from 5 minutes to 5 seconds, when starting program.
Adding exclusion:
Windows security → Virus & thread protection → Manage setting → Add or remove exclusions (bottom of the page) → Add an exclusion → Process → Type: Icedrive.exe → Add
I hope this will help someone