This article is about TruffleRuby, not jruby.
It's worth thinking about JRuby-performance-skeptical-ness when thinking about TruffleRuby due to some similarities. Not going to outline in a comment, but suffice it to say that TruffleRuby was once called JRuby+Truffle.
TruffleRuby has the power to work through JRuby shortcomings. With GraalVM, TruffleRuby gets to have C extensions! Graal is also open source, so we get more control of what we want it to do and more understanding of what it does. In theory, that gives TruffleRuby more room to get faster.
It's also worth noting Charles Nutter's comment on the post, that mentions that Hotspot C2 already does this optimization! (though they wouldn't have this kind of control over branch profiling)
> TruffleRuby started as my internship project at Oracle Labs in early 2013. It is an implementation of the Ruby programming language on the JVM, using the Graal dynamic compiler and the Truffle AST interpreter framework. TruffleRuby can achieve peak performance well beyond that possible in JRuby at the same time as being a significantly simpler system. In early 2014 it was open sourced and integrated into JRuby for incubation, then in 2017 it became its own project, and now it is part of GraalVM. Since 2019 Shopify has sponsored development.
> In early 2014 it was open sourced and integrated into JRuby for incubation
Additionally, we also tried Truffle when it was JRuby, or in JRuby, however you want to put it, but without a lot of success. Things could be different now.