Spring Boot vs Quarkus: Performance Test, Migration Guide, and When to Choose Each

Introduction

The article compares two popular Java back‑end frameworks—Spring Boot and Quarkus—by measuring their performance characteristics and discussing migration strategies for developers who want to run Java microservices on Kubernetes.

Spring Boot Overview

Spring Boot is a Java‑based framework that simplifies enterprise application development by providing auto‑configuration, starter dependencies, and a convention‑over‑configuration approach, which reduces boilerplate code and accelerates development cycles.

Quarkus Overview

Quarkus is a Kubernetes‑native Java framework built for OpenJDK HotSpot and GraalVM. It targets fast startup, low memory usage, and native image generation, making it well‑suited for containerized and serverless environments.

Comparison

Both frameworks integrate well with other Java libraries, but their internal architectures differ. Spring Boot offers both blocking (Servlet) and non‑blocking (WebFlux) web stacks, while Quarkus supports both models and embeds reactive programming directly in its core.

Test Application

A sample application implements three REST APIs for creating, retrieving, and searching postal codes using PostgreSQL. The APIs are built with the reactive programming model of Spring WebFlux and Quarkus.

Test Plan

Performance tests are executed with JMeter for five minutes, ramping up to 1,500 concurrent users. VisualVM monitors resource usage during the run. Both JVM and native builds are evaluated.

Results

Build Time

Quarkus builds a native image in 9 minutes versus 13 minutes for Spring Boot; JVM builds take 20 seconds for Quarkus and 39 seconds for Spring Boot.

Artifact Size

Native binaries are 75 MB (Quarkus) vs 109 MB (Spring Boot). JVM JARs are 4 KB (Quarkus) vs 26 MB (Spring Boot).

CPU Usage

During warm‑up, the JVM version of both frameworks consumes more CPU, after which usage stabilises across all variants.

Memory Usage

Quarkus reserves less heap from the start and shows lower peak memory consumption, although native images exhibit higher short‑term peaks that could be tuned with GC options.

Response Time & Throughput

Spring Boot JVM shows slightly better response times and can handle the same load with fewer threads, while Quarkus demonstrates strong low‑resource performance and comparable throughput.

Conclusions

Both frameworks are viable for Java microservices. Native Quarkus excels in startup speed and resource efficiency, making it ideal for serverless or short‑lived workloads, whereas Spring Boot JVM offers stable, high‑throughput performance for long‑running services.

Migration from Spring Boot to Quarkus

Quarkus provides Spring API compatibility (DI, Web, Data JPA) and can run most existing Java libraries without reflection, facilitating a smoother transition. The migration steps include creating a new Quarkus project, adding compatible extensions, and adjusting configuration.

Why Spring Developers Should Consider Quarkus

Reduced memory and CPU consumption.

Much faster startup (down to 0.0015 s for native images).

Supports both reactive and imperative programming models.

Compile‑time detection of CDI errors.

Combines the best of Spring, Vert.x, and MicroProfile standards.

Getting Started

Read the Quarkus introductory guide.

Review Spring DI, Spring Web, and Spring Data JPA documentation.

Generate a new project at code.quarkus.io.

Code Examples

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<Person> findAll() {
        return personRepository.findAll();
    }
}

package org.acme.springmp;

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

public interface PersonRepository extends CrudRepository<Person, Long> {
    List<Person> findByAge(int age);
}

Additional Resources

Further reading includes Baeldung’s Spring Boot vs Quarkus article, the official Quarkus blog for Spring developers, and LogicMonitor’s performance comparison.