Explore the development of YJIT, a new JIT compiler for CRuby, in this 30-minute conference talk from RubyConf 2021. Dive into the world of Ruby JITs, including TRUFFLE RUBY and its impressive performance improvements for Ruby Regexps. Learn about lazy basic block versioning, run-time value promotion, and the challenges of optimizing Ruby. Discover how to try YJIT, understand its current limitations, and maximize its performance. Gain insights into future plans for YJIT and the collaboration with Ruby core developers to enhance CRuby's performance.