Enabled composite is making videos tear.

[Felipe Morales]

1) Ubuntu 15.04

2) xfwm4: 4.12.1-1ubuntu1
driver: xserver-xorg-video-radeon: 1:7.5.0-1ubuntu2
gpu: amd radeon (ati) hd 5670 512mb gddr5
cpu: amd athlon II x2 240

3) Video playback with annoying tearing in:
    Online videos on Youtube (firefox)
    MP4 Videos (h264) on VLC/Smplayer

4) No tear.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: xfwm4 4.12.1-1ubuntu1
ProcVersionSignature: Ubuntu 3.19.0-15.15-generic 3.19.3
Uname: Linux 3.19.0-15-generic x86_64
ApportVersion: 2.17.2-0ubuntu1
Architecture: amd64
CurrentDesktop: XFCE
Date: Sun Apr 26 16:47:53 2015
ExecutablePath: /usr/bin/xfwm4
InstallationDate: Installed on 2015-04-26 (0 days ago)
InstallationMedia: Xubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422.1)
ProcEnviron:
 LANGUAGE=es_AR:es
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=es_AR.UTF-8
 SHELL=/bin/bash
SourcePackage: xfwm4
UpgradeStatus: No upgrade log present (probably fresh install)