Weirdly poor performance on 2016 Macbook Pro?

Brand new Macbook Pro with Touch Bar.

I’m getting very frequent dropouts and crackle even with a very light session (i.e. simple stereo playback or quad playback, no plugins) with Nuendo 7.1.20. VST Performance meter is down near the bottom, but with each crackle/dropout the red indicator goes on. (And consistent with this, if I turn on “Warn on Processing Overloads” in the prefs, then the “CPU Overload/Audio drop out detected” dialog opens each time.)

Because I installed on this computer via Migration Assistant, to troubleshoot I’ve gone so far as to uninstall completely
(following these guidelines: )
and download and reinstall from scratch – no change.

Fireface UC with newest drivers for MacOS Sierra 10.12.2.

Any ideas? Is this a problem with MacOS 10.12.2, or with this specific new model of Macbook Pro?