I just want to give you an update. I’m still investigating that issue and I’m pretty sure that I know what’s causing it. It seems it was introduced with the switch to kernel 4.9.
The problem seems to be located in the userland GPU library. Unfortunately, that library is closed source and we don’t have access to that code, so we can’t change/fix it. I’ve also tried to implement a workaround, and that made it slightly better, but also introduced some skipped frames as side effect 
. The adventure continues …