JDK 27 delivers over 2,300 commits with performance improvements across libraries, garbage collectors, JIT compiler, and runtime. Key features include Compact Object Headers enabled by default, G1 as the default garbage collector, and optimizations to HashMap bulk copies, AttributedString, URL.toString(), and file I/O operations, with reported improvements ranging from 35% to 86% in specific benchmarks.
Casita is a new content-addressed object store for source code and build artifacts, designed as a standalone layer of Nix rewritten in Rust. It provides shared storage, verification, synchronization, and garbage collection to efficiently manage the proliferation of build artifacts and source code versions produced by agentic development, available as a Rust library and CLI for Linux, macOS, and Windows.