How to tweak CoreGraphics:

Make sure you make a backup first.

Go to /System/Library/Frameworks/CoreGraphics.framework/Resources
Open up Configuration.plist
Make the following changes:

EnableErrorLogging
     Change this to "false"
    EnableVMPurging
     Change this to "true"
    ForceSessionDrawsVirtualFramebuffer
     Change false to "true"
    GLCompositorConfiguration

        GLCompositorMinimumDisplayDepth
        16
        GLCompositorMinimumVRAM
        16 Change "16" to "64"
        GLCompositorUseOnPortable

        tileHeight
        256
        tileWidth
        256

Then go down to:

</dict>
    SessionUsesVirtualFramebuffer
     Change false into "true"
    TransitionEffectMinimumDepth
    32 Change "32" to "16"