Undo and redo got slower (command + (shift) + z)

Undoing or redoing code changes got quite a bit slower after changing from 3.2.2 to 3.3.0.

I did a short comparison and timed a trivial editing operation by hand:

(1) Open an empty .h file, .cpp file or .txt file (doesn't matter which one)
(2) Press and hold enter to create about 60 new lines
(3) Press and hold command + z until all lines have been removed again.
(4) Press and hold command + shift + z until the 60 lines have been created again.

QtCreator 3.2.2:
(2) about 2 seconds
(3) about 3.5 seconds
(4) about 3.5 seconds

QtCreator 3.3.0:
(2) about 2 seconds
(3) about 8 seconds
(4) about 8 seconds

I would say my timing precision is about 0.5 seconds. My keyboard delay until repeat is set to shortest possible setting in the system preferences.