When dragging in OSX, mouse cursor movement is not smooth.
It is visible in all example applications where dragging is supported.

Just a drag without moving takes constantly up to 70% CPU time till drag is finished.

It makes it impossible to use drag'n drop quickly and precisely on OSX. Cursor jumps over screen.

Together with bug https://bugreports.qt.io/browse/QTBUG-48253 ( no retina support ) it is really not working as it should be.

No problem on Windows ( No matter how fast I move mouse when dragging in Windows it always ends in expected position, no jumps, just smooth mouse move. )