Explore the intricacies of compiling Java bytecode to JavaScript in this JSConf EU 2015 talk by Joa Ebert. Delve into the differences between JSVMs and their performance implications, examine the state of WebIDL and its significance, and uncover the relationship between types and optimizing compilers in AOT compilation. Learn about self-optimizing display lists, WebGL, and the WebAudio API in real-world applications. Gain insights into optimistic assumptions, deoptimizations, classloader support, and the benefits of running costly optimizations in the background. Discover the importance of simplifying JVM semantics for JavaScript, optimizing numeric operations, and the impact of prototype manipulation on performance across different browsers. Understand the significance of testing, measuring, and adapting to various browser optimizers. Explore techniques for optimizing display lists based on heuristics and caching vertices and culling information.