The latest version of Mesa can be downloaded from Softpedia
Mesa, an open source implementation of the OpenGL specification and a system for rendering interactive 3D graphics, is now at version 10.1.3.Mesa 10.1.3 is the next iteration in the series and implements the OpenGL 3.3 API. This means that some drivers might not support the specifications for the latest Mesa. After the previous version was made available, only a few days ago, a new one is now available for download and comes with just a few fixes.
"Mesa 10.1.3 is being released sooner than originally scheduled to make available a fix for a performance regression that was inadvertently introduced to Mesa 10.1.2. The performance regression is reported to make vmware swapbuffers fall back to software," reads the official announcement.
According to the changelog, MaxNumLayers for 1D array textures have been fixed, the depth (array slices) computation for 1D_ARRAY render targets has been corrected, bogus layout qualifier warnings have been fixed, and a performance regression introduced by commit "Cache render target surface" has been corrected.
More details about this release can be found in the official announcement. You can download the Mesa 10.1.3 sources right now from Softpedia. There is no binary file available, so it’s better to get the update from the official repositories.