Today I decided to do a clean install on MacBook Air - did an online recovery, erased the disk and installed MacOS High Sierra. Even clean it didn't behave really good so I decided to try Geekbench - with the Mac restarted and only the Geekbench app running - I got pretty low score - 1251 on single core and 2457 on multiple cores.
By a chance I had a Kali Linux (Debian) Live USB nearby so I decided to boot it and try Geekbench again. Got about three times better scores on both.
Got really suspicious and decided to wipe the Mac again and installed Ubuntu 17.10 to try the test again and it got an even better score - - 3294 on single core and 5773 on multiple cores.
It just feels much better - runs smoother, everything feels faster... Why could that be? I'm super confused. Can anyone shed some light on my case?