Spring Boot vs Quarkus: Which Backend Framework Wins in Performance and Cloud‑Native Efficiency?

Overview

Spring Boot is a well‑known Java framework; Quarkus is a newer Kubernetes‑native Java framework marketed as “Supersonic Subatomic Java”. It is built for OpenJDK HotSpot and GraalVM and aims to simplify development of containerised micro‑services.

Spring Boot

Spring Boot focuses on enterprise applications, provides convention‑over‑configuration, reduces boilerplate, and integrates many Spring projects out of the box, improving developer productivity.

Quarkus

Quarkus offers faster startup, lower memory usage, and smaller artifacts. It is optimized for cloud, serverless, and container environments and integrates well with popular Java libraries.

Comparison

Both frameworks integrate with other projects, but their internal architectures differ. Spring Boot supports blocking (Servlet) and non‑blocking (WebFlux) web stacks, while Quarkus supports both and embeds a reactive programming model.

Test Application

The test implements three APIs (create postal code, query postal‑code information, and city‑based lookup) using reactive features of Spring WebFlux and Quarkus, with PostgreSQL as the database.

Test Plan

JMeter runs a 5‑minute test that warms up the database, then ramps up to 1,500 concurrent users, while VisualVM monitors CPU and memory usage.

All tests were executed on a machine with the specifications shown below.

Results

Both projects provide a good developer experience, but Spring Boot has richer documentation. Quarkus is catching up.

Key findings:

Quarkus starts up almost twice as fast as Spring Boot in both JVM and native modes.

Build time: 9 min (Quarkus) vs 13 min (Spring Boot) for native images; 20 s vs 39 s for JVM builds.

Artifact size: native 75 MB (Quarkus) vs 109 MB (Spring Boot); JVM 4 KB (Quarkus) vs 26 MB (Spring Boot).

CPU

JVM versions consume more CPU during warm‑up; after that usage stabilises across all variants.

Memory

Both JVM variants reserve more heap memory, but Quarkus reserves less overall and shows lower utilization during startup.

Native Quarkus does not recycle memory as frequently as its JVM counterpart, but overall memory consumption remains lower.

Response Time

Spring Boot shows a slight advantage in response time and uses fewer threads for the same load, while its native version performs best in this scenario.

Spring Boot JVM benefits from JIT optimisation, leading to better throughput over time.

Overall, both frameworks handle all requests without errors and exhibit comparable performance.

Conclusion

Both Spring Boot and Quarkus are solid choices for Java applications. Native images provide fast start‑up and low resource consumption, ideal for serverless or short‑lived workloads, while JVM builds offer stability and high throughput for long‑running services.

Migrating from Spring to Quarkus

Quarkus was created by engineers with deep Spring expertise, ensuring strong Spring API compatibility (DI, Web, Data JPA, etc.) and easing the migration path.

Why Choose Quarkus as a Spring Developer

Quarkus optimizes memory usage and startup time, enabling up to twice as many instances on the same RAM and up to seven times more when compiled to native binaries. It also supports FaaS, live coding, reactive and imperative models, early DI error detection, and combines the best of Spring and MicroProfile standards.

Benefits for Spring Developers

Function‑as‑a‑Service: native binaries start in ~0.0015 s, enabling seamless use of existing Spring/Java APIs in serverless environments.

Live coding: changes are reflected instantly without restarts.

Support for both reactive and imperative programming models.

Compile‑time detection of dependency‑injection errors.

Best‑of‑both‑worlds framework combining Spring compatibility, Vert.x, MicroProfile, and reactive streams.

Getting Started with Quarkus

Read the Quarkus getting‑started guide.

Study the Spring DI, Spring Web, and Spring Data JPA guides.

Use code.quarkus.io to generate a new project.

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);
}

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();
    }
}