A lot of unnecessary screen updates with 5.10

-Start a Qt application (tested with Assistant)

-Put the focus in a text editing view to get a blinking cursor

-Start Quartz Debug and enable "Flash screen updates"

Qt 5.9 result: Only the blinking cursor gets flushed to screen

Qt 5.10 result: the whole window get flushed, every single blink.

Same happen when updating a progress bar, I have a 20% performance drop in my application from displaying a progress bar with Qt 5.10.