Were all of your tests using the 64-bit version of Firefox?

If you haven't already, could you test in Firefox's Safe Mode? In Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement? (More info: Diagnose Firefox issues using Troubleshoot Mode)

jscher2000 said

Were all of your tests using the 64-bit version of Firefox?

I believe so, i do not recall if i had the problem beforehand. Will test safe mode.

P.s. updated OP with further info.

Safe mode did not make a difference besides playback being not as smooth.

Is Netflix using the Silverlight plugin on either or both systems, or the built-in HTML5 player? Usually this can be determined from the right-click context menu for the video.

jscher2000 said

Is Netflix using the Silverlight plugin on either or both systems, or the built-in HTML5 player? Usually this can be determined from the right-click context menu for the video.

I have not installed silverlight on either system, also, there is no right-click context menu for the video. I suppose this means it's html5.

I think you're in new territory, but if the system have different graphics cards/chipsets and driver software, that's where I would look for the glitch vs. no glitch.

jscher2000 said

I think you're in new territory, but if the system have different graphics cards/chipsets and driver software, that's where I would look for the glitch vs. no glitch.

What do you mean new territory ? If it was a driver issue, wouldn't it be system wide ? Driver does not appear to be the problem as windows 10 installs with an older version. The problem persists with the older version and when i update to latest.

By new territory I mean you have Netflix working without Silverlight on a 64-bit Firefox. I haven't seen anything about that reported yet.

Firefox can have graphics driver incompatibilities even when other software is fine; apparently those kinds of glitches are hard to discover and fix in beta testing. But it's just a guess because otherwise your systems seem to be the same.

How is that new territory? Netflix switched to html5 quite a while ago(like 2014), no ? Ok, so it's firefox's incompatibility with nvidia drivers ?