Spring Boot vs Quarkus: Performance Comparison, Migration Guide, and Practical Code Samples

Spring Boot is a widely‑used Java framework for building enterprise applications, while Quarkus is a newer, Kubernetes‑native Java framework optimized for GraalVM native images and fast startup.

Spring Boot emphasizes convention‑over‑configuration, reducing boilerplate and providing extensive out‑of‑the‑box features that boost developer productivity.

Quarkus offers sub‑millisecond startup, lower memory footprints, and the ability to compile to native binaries, making it well‑suited for cloud‑native, serverless, and containerized workloads.

The two frameworks differ in web model support: Spring Boot provides both blocking (Servlet) and non‑blocking (WebFlux) options, whereas Quarkus supports both simultaneously and embeds a reactive programming model.

A performance test suite was built using JMeter and VisualVM to exercise three REST APIs (create, query by postal code, query by city) backed by PostgreSQL, running both JVM and native versions of each framework.

Results show Quarkus native images start roughly twice as fast as Spring Boot native, build in half the time, and produce smaller artifacts (75 MB vs 109 MB native, 4 KB vs 26 MB JVM). CPU usage during warm‑up is higher for JVM builds, while Quarkus consistently uses less memory; response‑time differences are modest, with Spring Boot JVM sometimes edging out.

Migration from Spring to Quarkus is facilitated by Spring API compatibility (DI, Web, Data JPA) and the ability to reuse existing Java libraries that avoid reflection, though some Spring features are not fully supported.

Additional benefits for Spring developers include FaaS readiness, live coding, combined reactive/imperative models, compile‑time DI error detection, and a rich set of extensions that blend Spring, MicroProfile, and Vert.x APIs.

Code examples demonstrate a simple Spring MVC controller, a Spring Data repository, and a Quarkus service using MicroProfile Fault Tolerance annotations, all wrapped in ... tags to preserve the original source.

To get started, readers are encouraged to follow the Quarkus getting‑started guide, explore Spring DI/Web/JPA documentation, generate a project at code.quarkus.io, and consult the listed reference links for deeper comparison and migration details.