DRI2 vs. DRI3 Radeon Linux OpenGL Performance

Following the recent Phoronix article about the state of DRI3 for X.Org drivers, many in the forums began discussing DRI3. While the Intel and Radeon X.Org drivers don't yet enable Direct Rendering Infrastructure 3 by default, I decided to run some fresh OpenGL benchmarks with a few Radeon graphics cards to compare the performance of DRI2 and DRI3.