Why do many teams delay adopting GraalVM native images despite the startup-time benefits in Spring Boot 4?

The benefits are real but narrow, while the costs land on every build, for every developer, regardless of whether the deployment shape actually needs them.

Build times for a native image are dramatically longer than a standard JAR build - what's a few seconds with a normal Maven/Gradle build can become minutes, which slows down CI feedback loops and makes local iterate-and-test cycles noticeably more painful. Some libraries, particularly ones that lean heavily on runtime reflection, dynamic proxies, or bytecode generation that isn't native-image-aware, need extra reachability metadata to work at all under AOT compilation, and a few simply don't work without workarounds or forks. Debugging a native binary also has far less mature tooling than attaching a debugger or profiler to a running JVM, which matters when something goes wrong in production.

Most importantly, the actual payoff - near-instant startup and a small, fixed memory footprint - matters most for specific deployment shapes: serverless functions that cold-start per invocation, or container-dense clusters that scale instances up and down frequently. A team running a modest, steadily-warm fleet of long-lived JVM instances doesn't experience those cold-start or density problems in the first place, so the reduced build speed and flexibility often isn't worth trading for a startup-time benefit that a warm, always-on JVM instance was never going to feel.