Scrolling lag with AMD GPU

[Sherif]

If I start Firefox with AMD GPU and force-enabling hardware acceleration, I get scrolling delay (Page updates, after few seconds from scrolling with the touchpad).
It only happens with AMD's GPU.

Bug happens also with Snap version and in Fedora.

Laptop: HP Pavilion g6.
CPU: Intel Core i5.
GPU: Radeon HD 7670.
RAM: 8 GB.

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: firefox (not installed)
ProcVersionSignature: Ubuntu 4.18.0-15.16-generic 4.18.20
Uname: Linux 4.18.0-15-generic x86_64
ApportVersion: 2.20.10-0ubuntu13.2
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sat Feb 16 01:17:38 2019
InstallationDate: Installed on 2019-02-07 (7 days ago)
InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Release amd64 (20181017.3)
SourcePackage: firefox
UpgradeStatus: No upgrade log present (probably fresh install)

[Sherif (ali-sherif10)]

Mozilla Bugzilla: https://bugzilla.mozilla.org/show_bug.cgi?id=1383563.