It is not that difficult to provide two backend for doing compositing. Enlightenment use the same backend as any EFL application for the compositing. That means both software and OpenGL (also GL ES) are provided. Software backend is faster than OpenGL in many scenario and also more stable (has it put less pressure on the driver). It is possible to use a Pentium at 600Mhz to do software compositing on 1024x800 screen without any speed issue. In fact, OpenGL is not a 2D API and is really not as efficient as a software implementation could be.