iMac 5K Late 2015 and Sierra=> choppy, unresponsive GUI

[Robert Johnson III]

Sierra and Reaper are (for me) almost unusable. Resizing Reaper goes choppy and slow, showing the mixer window takes seconds (no where near instant anyway) Selections with the Marque tool are choppy and slow etc…Using a scaled resolution and/or reduce transparency and/or a smaller Reaper window improves matters al little. The silly thing is that when I run reaper in a virtual desktop (VMware) with massive VMware CPU overhead, it runs fluid, contrary to native 5K on iMac (with all resources available). Any info from iMac 5K Late 2015 Sierra users on this?

Found this info…https://forum.qt.io/topic/59578/rend...with-retina-5k

Edit: (This post is about Reaper running on Sierra iMac 5K late 2015 27 inch Retina)