ubuntu 18.04 screen freeze sound jitter

https://askubuntu.com/questions/1065777/random-temporary-screen-lags-since-upgrade-to-18-04

The fix to my problem was a rather lengthy process. The final fix looks, in a nutshell, like this:

Re-add Drivers PPA -> Update -> Upgrade
Use Generic Kernel
Purge and Reinstall Graphics Drivers (just in case)
Configure the Card
Nuke local Chrome .config and Reinstall or (preferably) Switch to Firefox

Each action offers a slight improvement in performance culminating into a wonderfully performing system. The complete fix is as follows.

Proprietary GPU Driver PPA Disabled on Upgrade

First re-enable the graphics drivers ppa, and update drivers:

sudo add-apt-repository ppa:graphics-drivers/ppa
sudo apt update
sudo apt upgrade && sudo apt dist-upgrade

Use Generic Kernel When Low Latency is Not Required

I do audio production and so was using the low-latency kernel. It seems this kernel would give priority to audio and would allow the rest of the system to hang to keep audio in time.

I installed the generic kernel:

sudo apt install linux-generic

To use this kernel hold shift at boot and select advanced options and boot into generic kernel.

Purge and Reinstall Drivers

Tried upgrading to driver 396 using Software & Updates. After reboot, I could not start X. It wouldn't start automatically and the command startx makes the screen flicker then brings me back to the command line. (your mileage may vary)

Users in comments suggested I should purge and reinstall drivers, so I figured this was the perfect time to do so. So purged everything out:

sudo apt purge "*-nvidia-*"
sudo apt autoremove && sudo apt autoclean

Reboot and reinstall driver 390 (or 396 if it works for you) via Software & Updates and reboot.

sudo apt install nvidia-390