Eric proposed Mesa Drivers For Mesa at the beginning of August as a way to (slightly) boost performance by bundling all of the Mesa/Gallium3D drivers into a single .so shared library so that link-time optimizations could be applied to them as a whole by the compiler. Additionally, this method can save disk space and has some other benefits too.
Last week Eric Anholt provided an update on Mesa Mega Drivers during the XDC2013 conference. This afternoon, Eric released his initial patch-set for implementing this new driver concept model.
Eric posted his initial mega driver patch series to the Mesa mailing list and is noting about a 2.61% performance increase but with a 1.16% margin of error. This initial patch series also doesn't yet provide mega driver support to the Gallium3D hardware drivers but just namely core Mesa and the Intel classic driver. This initial work is spread across 14 patches.