Tradeoffs, Bad Science, and Polar Bears - The World of Java Optimisation

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Welcome to the Java optimisation jungle. Why can’t we “just make it go faster”? It turns out, in most cases, we need to first work out “faster for whom?” and “why do we want to go faster?” and “what even is faster?”

This talk introduces the basic principles of optimisation, before bouncing through the pitfalls of optimisation; why the exact same techniques which make Quarkus rocket-fast used to be a terrible idea fifteen years ago, why fast benchmarks make for slow programs, and why even though it can be easy to get wrong, optimisation really really matters. Along the way we’ll talk about measuring things, bad advice, garbage collection, and climate change.

Holly Cummins

Red Hat

Holly Cummins is a Senior Principal Software Engineer on the Red Hat Quarkus team. Before joining Red Hat, Holly was a long time IBMer. In her time at IBM, Holly has been a full-stack javascript developer, a WebSphere Liberty build architect, a client-facing consultant, a JVM performance engineer, and an innovation leader. During her time in the IBM Garage, Holly led projects for enormous banks, tiny startups, and everything in between. Holly has used the power of cloud to understand climate risks, count fish, help a blind athlete run ultra-marathons in the desert solo, and invent stories (although not at all the same time). Holly is also a Java Champion, author, and regular keynote speaker. You can follow her on twitter at @holly_cummins or at