Awful full-screen scrolling performance

Hi,

Mac OS - High Sierra 10.13.3

iMac 27" 2017 model

16gb RAM

Adobe Audition 11.0.1.49

When full-screen, auto-scrolling, the performance is just awful. Juddery, jumpy and pretty much unusable so have to reduce window size, pretty much wasting the 5k screen.

Here is crappy video showing judder-city.

File 02 02 2018, 14 43 47 - YouTube

I have both waveform and spectral view running as you can see.

I saw this in the release notes for latest version:-

• Improvements to Center-Scrolling behaviors – smoother scrolling, no more jumping

But I don't see any improvement.

Surely a machine of my spec should be able scroll smoothly?

Ideas?

Mark