I am a long time developer with alot of experience in the mobile field.
I feel now that the field I am lacking in is the understanding of the UI internals and performance, maybe more in the traditional computer graphics field.
I am looking for recommended sources for adding understanding in these areas, hopefully without reading through entire bibliography on OpenGL etc.
Is this possible and what are some recommended sources?
Check http://www.RayWenderlich.com there are a ton of graphics related tutorials there form 2D to 3D including CoreGraphics and OpenGL.
Also the Apple documentation has some good information on graphics performance. You really should just dive in then post specific questions here.