Actually it seems that the cause is the new xserver-xorg-core, it seems that XAA rendering was ripped out from 1.15.1 (no libxaa.so in package).
In old Xorg.0.log rendering was falling back to XAA: [ 4.696] (II) MGA(0): Using XFree86 Acceleration Architecture (XAA) [ 4.696] Screen to screen bit blits [ 4.696] Solid filled rectangles [ 4.696] Solid filled trapezoids [ 4.696] 8x8 mono pattern filled rectangles [ 4.696] 8x8 mono pattern filled trapezoids [ 4.696] Indirect CPU to Screen color expansion [ 4.696] Screen to Screen color expansion [ 4.696] Solid Lines [ 4.696] Dashed Lines [ 4.696] Scanline Image Writes [ 4.697] Setting up tile and stipple cache: [ 4.697] 32 128x128 slots [ 4.697] 22 256x256 slots [ 4.697] (==) MGA(0): Backing store disabled [ 4.697] (==) MGA(0): Silken mouse enabled [ 4.698] (==) MGA(0): DPMS enabled [ 4.698] (WW) MGA(0): Direct rendering disabled [ 4.698] (==) RandR enabled [ 4.707] (II) AIGLX: Screen 0 is not DRI2 capable [ 4.707] (II) AIGLX: Screen 0 is not DRI capable [ 4.800] (II) AIGLX: Loaded and initialized swrast [ 4.800] (II) GLX: Initialized DRISWRAST GL provider for screen 0 In 14.04 there is no XAA acceleration anymore [ 8233.057] (EE) MGA(0): [drm] Direct rendering only supported with G200/G400/G450/G550. [ 8233.057] (II) MGA(0): Using 3289 lines for offscreen memory. [ 8233.057] (==) MGA(0): Backing store enabled [ 8233.057] (==) MGA(0): Silken mouse enabled [ 8233.057] (==) MGA(0): DPMS enabled [ 8233.057] (WW) MGA(0): Direct rendering disabled [ 8233.057] (==) RandR enabled [ 8233.062] (II) SELinux: Disabled on system [ 8233.062] (II) AIGLX: Screen 0 is not DRI2 capable [ 8233.062] (EE) AIGLX: reverting to software rendering [ 8233.074] (II) AIGLX: Loaded and initialized swrast [ 8233.074] (II) GLX: Initialized DRISWRAST GL provider for screen 0 unfortunately without XAA moving a window is like a slug -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/1316035 Title: matrox g200eR2 is unclaimed in 14.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1316035/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp