Ask Slashdot: What's the Fastest Linux Distro for an Old Macbook 7,1?

Long-time Slashdot reader gr8gatzby writes: I have an old beautiful mint condition white Macbook 7,1 with a 2.4Ghz Core 2 Duo and 5GB RAM. Apple cut off the upgrade path of this model at 10.6.8, while a modern-day version of any browser requires at least 10.9 these days, and as a result my browsing is limited to Chrome version 49.0.2623.112.

So this leaves me with Linux. What is the fastest, most efficient and powerful distro for a Mac of this vintage?
It's been nearly eight years since its release, so leave your best thoughts in the comments. What's the best Linux distro for an old Macbook 7,1?