Rails Speed with Ruby 2.4.0 and Current Discourse

My recent benchmarking blog posts looked at how Rails and Discourse performance changed from Ruby 2.0.X to 2.3.X But they have a glaring, huge omission: they stop at Ruby 2.3.4 and at Discourse 1.5.0 (vintage March 2016.) That covers a lot of the post-Ruby-2.0 performance improvements, but what's changed between 2.3.4 and the latest Ruby?Unfortunately, the Discourse version we used, 1.5.0, doesn't support Ruby 2.4 or higher. It's a risk with using a real app for benchmarking. New Discourse only supports Ruby 2.3 or 2.4. So: let's look at current Discourse's speed on Ruby 2.3.4 and Ruby's head-of-master in Git.