Okay so it is quicker to load. Once the splash screen is visible (which seems to take longer!) the Ready page appears in a couple of seconds. Unfortunately the stuttered playback remains (HD CDNG). I even went back to 17.1.1 this morning to check and it is much smoother with no dropped frames in the Edit page.
After the Update just trying to do some simple Text3D & keeps crashing before I get very far. TEXT3D Node Render3D Node display on Screen 2, go to move text, stalls for a few seconds then crashes