Comparing Spring Boot and Quarkus: Performance, Native Images, and Migration Guide

Overview

Spring Boot is a well‑known Java framework for building enterprise applications, while Quarkus is a newer Kubernetes‑native Java framework optimized for OpenJDK HotSpot and GraalVM. The article presents a side‑by‑side comparison of the two frameworks, including performance tests and migration advice.

Spring Boot

Spring Boot simplifies development by providing convention‑over‑configuration, auto‑registration of defaults, and a rich ecosystem of starter dependencies, which reduces boilerplate code and speeds up the development cycle.

Quarkus

Quarkus offers faster startup, lower memory footprint, and the ability to produce small native binaries. It is optimized for cloud, serverless, and container environments and integrates well with popular Java libraries.

Comparison

Both frameworks integrate with many projects, but their internal implementations differ. Spring Boot supports blocking (Servlets) and non‑blocking (WebFlux) web stacks, while Quarkus supports both and embeds a reactive programming model. The comparison uses fully reactive applications built with Spring WebFlux and Quarkus reactive extensions, and also evaluates native images built with GraalVM.

Test Application

The sample application implements three APIs for creating, querying, and searching postal codes using PostgreSQL as the data store. It is deliberately more complex than a simple HelloWorld to reflect realistic workloads.

Test Plan

JMeter is used to drive a 5‑minute load test that ramps up to 1,500 concurrent users, while VisualVM monitors resource usage. All tests run on a specified hardware configuration.

Results

Quarkus shows roughly double the startup speed of Spring Boot in both JVM and native modes, and builds native images in 9 minutes versus 13 minutes for Spring Boot. Artifact sizes are also smaller (75 MB vs 109 MB for native, 4 KB vs 26 MB for JVM).

CPU

During warm‑up, the JVM version consumes more CPU, after which usage stabilizes across all variants.

Memory

Both JVM variants reserve more heap memory, but Quarkus starts with a lower memory reservation and uses less memory overall, despite occasional higher peaks in native mode.

Response Time

Spring Boot slightly outperforms Quarkus in response time and thread usage, especially in the native build, though both frameworks handle the load without errors.

Conclusion

Both frameworks are viable for Java microservices. Native builds are ideal for serverless or short‑lived workloads due to speed and low resource consumption, while JVM builds offer stability and high throughput for long‑running services.

Migrating from Spring to Quarkus

Quarkus provides Spring API compatibility (DI, Web, Data JPA) and is backed by engineers who also support Spring Boot on Red Hat Runtime, easing the migration path.

Why a Spring Developer Should Choose Quarkus

Quarkus addresses the challenges of containerized, Kubernetes‑driven environments by reducing memory usage and startup time, enabling higher instance density and better resource efficiency.

Additional Benefits for Spring Developers

Fast Function‑as‑a‑Service (FaaS) startup (≈0.0015 s for native binaries).

Live coding without restarts.

Support for both reactive and imperative programming models.

Compile‑time detection of dependency‑injection errors.

Combination of the best frameworks and standards (Spring API, Eclipse Vert.x, MicroProfile, reactive streams, messaging).

Getting Started

Recommended steps: read the Quarkus getting‑started guide, explore the Spring DI, Spring Web, and Spring Data JPA guides, and generate a new project at code.quarkus.io .

Reference Links

See the listed URLs for detailed articles, blogs, and documentation.

Code Examples

Spring‑compatible controller:

import java.util.List;
import java.util.Optional;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/person")
public class PersonController {
    @GetMapping(path = "/greet/{id}", produces = "text/plain")
    public String greetPerson(@PathVariable(name = "id") long id) {
        String name = "";
        // ...
        return name;
    }

    @GetMapping(produces = "application/json")
    public Iterable
findAll() {
        return personRepository.findAll();
    }
}

Quarkus Spring Data repository:

package org.acme.springmp;

import java.util.List;
import org.springframework.data.repository.CrudRepository;

public interface PersonRepository extends CrudRepository
{
    List
findByAge(int age);
}

Quarkus service with MicroProfile fault tolerance:

import org.eclipse.microprofile.faulttolerance.Fallback;
import org.eclipse.microprofile.faulttolerance.Timeout;
import org.eclipse.microprofile.rest.client.inject.RestClient;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;

@Service
public class PersonService {
    @Autowired
    @RestClient
    SalutationMicroProfileRestClient salutationRestClient;

    @Value("${fallbackSalutation}")
    String fallbackSalutation;

    @CircuitBreaker(delay = 5000, failureRatio = .5)
    @Fallback(fallbackMethod = "salutationFallback")
    public String getSalutation() {
        return salutationRestClient.getSalutation();
    }
}