Bumblebee is the current workaround for using Nvidia optimus with linux.
At the heart of bumblebee has been VirtualGL which is now being superseded by Primus.
If you have Bumblebee you'll know that to use your discrete card you need to invoke
optirun application from the command line and then after a short wait your application runs using the VirtualGL backend.
Unfortunately the VirtualGL backend does not play nice with some applications, particularly Wine and Crossover.
Primus is the replacement of optirun and it all it means to the end user is that instead of using optirun you now invoke an app with
The developers of Bumbleebee highly recommend primus over VirtualGL because there are a host of benefits.
One benefit is that it works perfectly with Wine and Crossover meaning You can play your Windows games on your discrete card instead of having to use your integrated one and has substantially better performance too.