Unity panel partially unresponsive

The menu bar of my Ubuntu 16.04 is presenting continuously problems consisting on seemingly random freezes or interaction lag.

For example, if I click a menu or indicator item, the item will become highlighted but the menu would take several seconds to appear or wont appear at all. Some times, if I continue interacting with many items on the Panel the clock will freeze, then the Dash wont show, then the Alt+Tab wont work, then the whole desktop will become unresponsive (but the applications won't crash). At this point I could switch to tty1 then back to GUI then Unity will crash and restart and I would be able to continue working normally.

Currently I'm using an Nvidia GTX 1060 card with proprietary drivers v.378.13 and I'm almost sure that the problem started when I added this GPU to my PC. Before I only used my i5 4670 integrated Intel HD 4600 and don't remember having this issue.

I'm unsure of the trigger but have noticed that it happens more often after I watch a video (single or many) in full screen, be it Flash in the browser or in MPV. Not always though. Some times I can watch hours and the problem wont show. Or I can watch none and the problem will manifest. I suspect also of hardware accelerated browser since I have always Opera or Firefox open, but nothing conclusive.

I've consulted syslog, Xorg.0.log and lightdm logs for clues, but haven't found anything relevant but I'm just a power user, so might have missed something.

Any clue on how to approach and pinpoint this problem?