Java Performance Update: From JDK 21 to JDK 25

JDK 25 has arrived, bringing a major set of performance gains over JDK 21—often letting your existing, unchanged Java applications run faster right away. In this talk, we’ll dive into 13 concrete performance improvements delivered between JDK 21 and JDK 25 across the standard libraries, the JIT compiler, and garbage collectors.

Along the way, you’ll get an inside look at the design tradeoffs behind these optimizations and how JDK engineers evaluate performance in the real world—where platforms differ and optimization goals can conflict.

We’ll also spotlight one of the most exciting new additions: the preview feature Stable Value, which lets a field combine key benefits of both mutable and immutable data. You’ll learn how Stable Value works, what kinds of speedups it can unlock, and how you can start taking advantage of it today.

Presented by *Claes Redestad* and *Per Minborg* (Java Platform Group - Oracle) during *Jfokus* 2026 ➤ https://www.jfokus.se

More on Performance ➤ https://inside.java/tag/performance

Tags: #Java, #Performance, #JVM, #OpenJDK