Ask HN: Updating a Mid 2012 MacBook Pro OS X 10.8.5?

I'm interested in taking a Udacity course, but the technology course requirements state that the operating system for Macs should be OS X 10.11 and higher.

I was always content with leaving my MacBook Pro at OS X 10.8.5. I'm a little bit hesitant about what will happen with my machine after updating. Will it run a lot slower, or should I be fine? Also, should I update to OS X 10.11 or higher?

Thanks.