I'm running Pro Tools 12.7.1 and just upgraded to Sierra and I'm finding the fader redraw is very laggy. I'm at 12% system usage on a track without any plugins on it just adjusting the volume with my mouse and the fader is jumping around like I'm on the verge of running out of resources.
I'm running a late 2014 MBP 2.8GHz quadcore, 16GB ram and 512 SSD and Apollo silver face via Thunderbolt
UPDATE: Two things seem to get rid of fader lag. 1) zooming out. On my system the lag only occurs when I'm zoomed in a bit. 2) If I can not see the playhead (ie while playing scroll to where the playhead is not visible). This doesn't fix anything but on my system faders do not lag under these circumstances.