client-side GPU offloading for NVIDIA Optimus

 Primus is a shared library that provides OpenGL and GLX APIs and implements
 low-overhead local-only client-side OpenGL offloading via GLX forking,
 similar to VirtualGL. It intercepts GLX calls and redirects GL rendering
 to a secondary X display, presumably driven by a faster GPU. On swapping
 buffers, rendered contents are read back using a PBO and copied onto
 the drawable it was supposed to be rendered on in the first place.
 .
 Primus is currently intended to be used alongside Bumblebee and provides a
 drop-in replacement for optirun (i.e. "primusrun").