I’ve wondered Why Rails becomes slow with JIT for a long time. Today, I’m pleased to share my answer to the question in this article, which I spent three years of my life to figure out. RubyKaig 2018 / The Method JIT Compiler for Ruby 2.6"MJIT Does Not Improve Rails Performance"As I wrote in Ruby 3.0.0 Release Note and my previous post, we thought: it is still not ready for optimizing workloads li