1.     Double click on ☁️ iCloud icon in finder to see progress.
2.     Go to Terminal
    ps aux | grep bird
3.     Identify PID for bird(responsible for icloud sync) 815 in the case below
    serg               815  98.8  0.8  4542828 137776   ??  U    Thu09PM 2047:53.94 /System/Library/PrivateFrameworks/CloudDocsDaemon.framework/Versions/A/Support/bird
4.     check prority of the process(default 0)
    ps -fl -C 815
5.     Change priority (lower = more important. 20 said to be max but be safe)
    sudo renice -n -10 -p 815