One diagonal part of the screen does not update at same time as other part, randomly

[Red Squirrel]

Best way I can explain it, on my laptop at work, when scrolling or doing anything that produces lot of movement on the screen, occasionally I can see a diagonal line through the screen, it's not really a line, like a solid color, but rather that one part of the screen is not scrolling at the same rate as the other, by like a few ms. This shows up pretty badly if watching Youtube in full screen.

I had something similar happen to my system at home, and there's a setting in about:config that fixes it, but I can't actually recall what it is. It seems to only be an issue in Linux, but since it's mostly noticeable in Firefox itself changing the setting does help. Anyone happen to be familiar with this issue and know the setting? I know there's also disabling hardware acceleration but that's already disabled.

 

[Red Squirrel]

Anyone have any ideas? This is super annoying. I found a couple things online but nothing seems to be working so far. Disabled hardware acceleration in FF (I thought it was already disabled but guess not) and also created a xorg file as follows:

/etc/X11/xorg.conf.d/20-intel.conf

Section "Device"
  Identifier  "Intel Graphics"
  Driver      "intel"
  Option      "TearFree" "true"
EndSection

I found other stuff about going to certain parts in the settings but I don't get any of those options. There's a place where I have to disable an option called "compositing" but I can't find that option anywhere.

Distro is Linux Mint. I don't recall which version, I think it's Cinnamon.

 

[Red Squirrel]

I decided to try another desktop environment to see if it fixes the issue. I switched to XFCE. While it did fix the issue now of course I have a new problem. The sound is all screwed up. The volume controls on the keyboard did not work so I found a solution, but now mute is all messed up. When I mute, instead of only muting the "master" it also mutes the "headphone" which the speakers are plugged in. When I unmute, that one stays muted. I have to go screw around in the sound mixer every time. Since this is a work laptop I use mute/unmute a lot because if a phone call comes in I need to be able to quickly mute anything that is playing. it's faster to hit the button than to move the mouse to whatever is playing and stop it. So this needs to work.

Any way to fix this? I googled it and it's a known bug from like 2012 but I have yet to find any detail on how to fix it. This is the part of Linux I find so frustrating. These are quircks that should not even exist. Even Windows 95 had this stuff working fine.

Edit: Ok got sound working through trying a whole bunch of stuff that I don't remember, but the one that did it was to right click on the speaker icon and going properties, and then selecting the "sound card" drop down to be "playback: built-in audio analog..."

I don't know if some of the other stuff I did prior also contributed. What a pain though. Should not have to do this kind of crap, it should just work by default.