standard help desk phrase: did you reboot already?

I do have this phenomenon on my JollaC when scrolling the browser window content

But iirc this may have to do with fragmented swap or similar. You should find something here on TMO.

If a normal reboot does not help, please do:
shutdown
pull off battery
wait for 30 seconds (you may push power button for 3 seconds)
push in battery
startup