I see similar thing on my 5.1 but with some material and not sure if the same amount
you have.
What sometimes fixes it for me is zooming in a bit as the lag seems to me stronger
when all zoomed out like UI refresh would do that.
—
Margus
https://iconstudios.eu
https://vimeo.com/iconstudioseu/videos
DaVinci 10, OSX 10.8.5
MacPro 5.1 2×2,93 24GB
GUI 4000 / GPU GTX 780
DL 4K
Eizo Color
Scope Box
Full Ligthspace CMS