Summary
JetBrains and Azul are collaborating on a shared vision of running Kotlin-generated bytecode on a high-performance Java platform to find new ways to enhance runtime performance. Benchmarks of Kotlin performance on Azul Platform Prime have yielded some eye-opening results.
In this post you will learn:
- Kotlin is a high-level programming language designed to interoperate fully with the JVM
- Runtime performance and scalability are derived predominantly from the JVM
- JetBrains and Azul benchmarked Kotlin on both standard OpenJDK and on Azul Platform Prime, a high-performance Java platform
- Platform Prime reduced latencies by 23.9% and improved throughput by as much as 30.5%
As modern JVMs combine language features and runtime optimizations, they unlock new levels of performance.
JetBrains developed the Java-based Kotlin language and released the first stable version in 2016. In 2019, Google officially endorsed Kotlin as its preferred language for Android development for its scalable code and expressive features. Those features include Coroutines, a concurrency design pattern for writing more readable asynchronous code, and inline classes that mitigate potential performance hits.
Azul Platform Prime includes Azul Zing, an award-winning enhanced build of OpenJDK, featuring the optimized Falcon JIT compiler and the C4 Pauseless Garbage Collector, to help maximize runtime efficiency.
Earlier in 2025, JetBrains and Azul collaborated on a shared vision of running Kotlin-generated bytecode on a high-performance Java platform to find new ways to enhance runtime performance. While Kotlin is a cross-platform, general-purpose high-level programming language, runtime performance and scalability are derived predominantly from the JVM
Benchmarking Kotlin performance on Azul Platform Prime
In May, JetBrains and Azul benchmarked Kotlin on Platform Prime versus Kotlin on standard OpenJDK. JetBrains selected a Kotlin project from the TechEmpower Framework Benchmarks, an industry-recognized open-source project that reflects typical backend workloads. The test exercised object-related mapping, database connectivity, dynamically sized collections, sorting, server-side templates, and other standard operations. JetBrains ran applications that perform CPU-intensive and memory-intensive operations on both standard OpenJDK and Azul Platform Prime, and tested them under high load.
Apart from using different JDKs, the test machines were identical.
They found the following results:
| Tech-Empower | CPU-intensive | Memory-intensive | |
|---|---|---|---|
| Latency average | 23.9% | 28% | 27.8% |
| Throughput | 30.5% | 39% | 38.1% |
The performance enhancements observed can be attributed to key Platform Prime technologies:
- ReadyNow Orchestrator: Accelerates Java warmup times for modern applications running in container, elastic, autoscaling cloud environments with contemporary DevOps practices. Solve the Java warmup problem
- Falcon JIT compiler: Utilizes LLVM-based optimization techniques, enabling deeper optimizations and improved throughput. This directly enhances the execution efficiency of bytecode generated by the Kotlin compiler. Prepare to run faster Java code
- C4 Pauseless Garbage Collector: Continuously manages memory concurrently without “stop-the-world” pauses, significantly reducing latency spikes and maintaining consistent response times, particularly beneficial for coroutine-intensive Kotlin applications. Provide more stable Java applications
| Learn more about Kotlin performance on Azul Platform Prime |
|---|
| Kotlin and Azul: Collaboration for Enhanced Runtime Performance Azul and JetBrains Collaborate to Enhance Runtime Performance for Kotlin Workloads |
What’s next for JetBrains and Azul?
Encouraged by these findings, JetBrains and Azul have established new objectives:
- To expand benchmark coverage by adding various real-world use cases. The Azul team will also add Kotlin projects for regular testing of their JDK distributions.
- To delve deeper into potential bytecode-level optimizations within the Kotlin compiler itself. The Azul engineering team will advise us on JVM requirements for bytecode optimizations. With this data, Kotlin’s compiler team will explore targeted changes in bytecode generation that could further boost runtime performance.
On May 20, JetBrains and Azul announced a strategic technical collaboration to enhance the runtime performance and scalability of web and server-side Kotlin applications. This strategic collaboration empowers Kotlin teams to accelerate development cycles and optimize application performance, helping them support their business priorities while driving greater operational efficiency.
Future collaboration includes Kotlin-specific optimization and reusing JIT compilation for Coroutines / interface Continuation. Learn more in a live joint webinar with JetBrains and Azul.
On September 10, JetBrains Developer Advocate Simon Vergauwen and Azul Senior Product Manager Jiří Holuša will present How to Boost JVM Scalability and Performance with Kotlin and Azul Runtime, a live webinar on the benchmarks and what’s next in the collaboration between JetBrains and Azul.
