This patch disables mouse coalescing on OS X, thereby producing a 3 to 4 times higher frequency of mouse/table move events.
For reproducing its effects, this patch includes some low quality debug code triggered via DEBUG_TABLET_MOVE_DT.
Testing on an iMac 5K (4 GHz i7, AMD Radeon R 9), maximum times between consecutive tablet move events while drawing went from about 35 ms to 9 ms.
without patch:
with patch:
This is my first Phabricator patch.