OK Henri, I should have made it into a new topic after all, cause Mr Tach was on experimental branch. Sorry, I misread.
So, it appears that always chasing the latest graphic driver even for a mildly olg GC is not always a good thing, huh?
Indeed, I also have Cool VL 1.30.0.21 running on Linux, on my secondary and older PC (Geforce GTX 660 with 470.141.03 drivers). On that one, the viewer reveals rock stable even with GL Worker Thread set to -1 (auto). Quite embarrassing. For my main setup I mean...