Poor DisplacementMap effect performance on Mac

*NOTE: This JIRA is also tracking the performance issue RT-28752. Before this is marked fixed, it is important to run the tests from this JIRA and generally make sure it is also fixed.*


Steps to reproduce:
1. Open BookPanel project
2. Run bookpanel.BendingPagesTest from Test Packages
3. Drag the right bottom edge of the page.
Observe poor performance (~5-6 fps) with Renderer: NVIDIA GeForce GT 650M OpenGL Engine.
At the same time performance tracker reports ~60 fps.

You could also run the automated version (booktest.BeagleboardTest) which does the same using Timeline. The effect is very smooth and actually appearing at 60 fps.


On Windows with the following driver performace is at ~45 fps
D3D Driver Information:
NVIDIA NVS 4200M
\\.\DISPLAY2
Driver nvd3dumx.dll, version 8.17.12.9679
Pixel Shader version 3.0
Device : ven_10DE, dev_1056, subsys_04931028