Faster rendering is mainly relevant to games that do not support frameskip (eg. games that use video capture to output 3d graphics to both screens) from my testings, games with two-dimensional polygon graphics are ca. 2x faster than with opengl (that including the cpu emulation, so the 'raw' rendering is apparently a lot faster). games with three-dimensional graphics are somewhat 1.6x faster than with opengl. above values are meant relative to microsoft's generic opengl driver, timings might eventually differ with drivers from other manufacturers. aside from faster emulation, the new software renderer additionally supports edge-marking, toon-table, and more accurate polygon sizes and positions. current version does still include an option for re-activing the old opengl renderer (for testing and comparision purposes) (there's also a new option to disable rendering, just to see how fast it could get without the 3d stuff).
The 3D rendering engine is now almost twice as fast as in v2.6, parts due to using MMX code, parts due to general optimizations. Most games aren't running that much faster, though the improvement may be significant in games that have high rendering load combined with little cpu load.
The new Auto Backup detection does detect the correct type when starting the game, and (theoretically) it should properly save data later on in the game (though without at least a gigahertz computer, it'd be a pain to verify that).
