Spring Boot vs Quarkus: Comparative Performance Analysis and Migration Guide

1 Overview

Spring Boot is a well‑known Java framework; Quarkus is a newer Kubernetes‑native Java framework marketed as “Supersonic Subatomic Java”. This article compares the two frameworks, discusses their differences, and presents performance tests.

2 SpringBoot

Spring Boot simplifies Java enterprise development with convention‑over‑configuration, reducing boilerplate and providing many out‑of‑the‑box features.

3 Quarkus

Quarkus offers faster startup, lower memory usage, and native image support, optimized for cloud, serverless, and container environments while remaining compatible with popular Java libraries.

4 Comparison

Both integrate well with other projects, but differ internally. Spring Boot offers blocking (Servlet) and non‑blocking (WebFlux) web stacks; Quarkus supports both and embeds a reactive programming model. The test uses reactive implementations of the same APIs.

Test Application

The sample implements three APIs (create, query by zip code, query by city) using Spring WebFlux and Quarkus reactive features with PostgreSQL.

Test Plan

JMeter runs a 5‑minute test with up to 1500 concurrent users, measuring CPU, memory, and response time. Tests are executed on specified hardware.

5 Results

Quarkus native builds start roughly twice as fast as Spring Boot native, with smaller artifact sizes (75 MB vs 109 MB native, 4 KB vs 26 MB JVM). CPU usage is higher at warm‑up for JVM builds, but overall similar. Memory usage is lower for Quarkus, especially in native mode.

CPU

JVM versions consume more CPU during warm‑up; later usage stabilises.

Memory

Quarkus reserves less heap initially and uses less memory during execution, though native GC behaviour differs.

Response Time

Spring Boot JVM shows slightly better response times and lower thread count, while Quarkus excels in low‑resource scenarios.

6 Migration from Spring to Quarkus

Quarkus provides Spring API compatibility (DI, Web, Data JPA) and is built by engineers with deep Java expertise, easing migration.

7 Why Spring developers should consider Quarkus

Quarkus is optimized for Kubernetes, offering faster startup, lower memory, and native compilation, making it suitable for serverless and short‑lived workloads.

8 Leveraging existing Spring knowledge

Quarkus supports Spring DI, Web, Data JPA, and many Java libraries that avoid reflection, allowing gradual adoption.

9 Additional benefits for Spring developers

Function‑as‑a‑Service with native binaries.

Live coding without restarts.

Support for both reactive and imperative models.

Compile‑time detection of DI errors.

Combination of best‑of‑both‑worlds frameworks.

10 Getting started with Quarkus

Read the Quarkus getting‑started guide.

Follow Spring DI, Web, and Data JPA guides.

Generate a project at code.quarkus.io.

Code Example: Spring 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<Person> findAll() {
        return personRepository.findAll();
    }
}

Code Example: Spring Repository

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);
}

Code Example: Quarkus Service with MicroProfile

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 // Spring
public class PersonService {
    @Autowired // Spring
    @RestClient // MicroProfile
    SalutationMicroProfileRestClient salutationRestClient;

    @Value('${fallbackSalutation}') // Spring
    String fallbackSalutation;

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