YJIT 3.4: Even Faster and More Memory-Efficient | Rails at Scale

It’s 2025, and this year again, the YJIT team brings you a new version of YJIT that is even faster, more stable, and more memory-efficient.Last year’s YJIT release delivered an impressive performance boost which earned us multiple shoutouts on social media. I was pleasantly surprised to hear that many large businesses running Rails in production had upgraded to the latest version of Ruby, in part because they were excited to get better performance. I distinctly remember, when I started at Shopify, before YJIT was a thing, that most Ruby deployments were several versions behind. Seeing many people deploying the latest Ruby with YJIT enabled left me with a warm fuzzy feeling that we had made a difference in terms of Ruby adoption. Performance really is the carrot that gets people excited.