I'm a little out of the loop on this subject, so I thought I'd ask you fine knowledgeable folks. What is the latest/best performing OS to use for a 2009 white unibody Macbook, running an SSD and 8GB RAM. Otherwise, the usual stock specs: 2.26Ghz C2D, GeForce 9400M, etc. I don't want to upgrade to Sierra and have it be unnecessarily slow. This will be a glorified internet machine for a family member. Thanks!