YJIT 3.4: Even Faster and More Memory-Efficient

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.

Historically, we’ve compared the performance of YJIT to that of the CRuby interpreter, which makes for some impressive numbers. For instance, as of this writing, on our x86-64 benchmarking setup, YJIT 3.4 is ~92% faster than the interpreter across the headline benchmarks we track. However, this year marks the 4th YJIT release, and as such, we’re going with the assumption that many production deployments already have YJIT enabled, and will be upgrading from Ruby 3.3 + YJIT to Ruby 3.4 + YJIT, rather than upgrading from a deployment with YJIT disabled.

Leave a Comment