10 Proven Ways to Speed Up Spring Boot Startup Time

Spring Boot is a widely used Java framework that simplifies Spring‑based application development, but its startup time can become a critical issue. The following practices help accelerate Spring Boot startup.

1. Lazy Loading

Spring Boot 2.2+ supports lazy loading, reducing CPU and memory usage during startup.

@SpringBootApplication
public class MyApplication {
    public static void main(String[] args) {
        SpringApplication app = new SpringApplication(MyApplication.class);
        app.setLazyInitialization(true); // Enable lazy loading
        app.run(args);
    }
}
// By setting setLazyInitialization to true, only essential beans are loaded at startup; others are created on first use.

2. Lazy Database Initialization

Deferring database connection initialization shortens startup time.

# application.properties
spring.datasource.initialization-mode=lazy
// This setting makes the datasource initialize lazily.

3. Reduce Auto‑Configuration Classes

Exclude unnecessary auto‑configuration to avoid unnecessary processing.

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
public class MyApplication {
    // ...
}
// The exclude attribute removes unneeded auto‑configuration classes.

4. Optimize Log Levels

Excessive logging can degrade startup performance; set a reasonable log level.

# application.properties
logging.level.root=WARN
// Setting root log level to WARN reduces log output.

5. JVM Parameter Tuning

JVM startup flags significantly affect Spring Boot launch time.

java -Xmx512m -Xms512m -jar myapp.jar
// Sets max and min heap size to 512 MB (adjust as needed).

6. Trim Dependencies

Removing unused dependencies reduces the amount of code the JVM must load.

<!-- pom.xml -->
<!-- Example: remove an unnecessary Spring Boot starter -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
    <exclusions>
        <exclusion>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-logging</artifactId>
        </exclusion>
    </exclusions>
</dependency>

7. Optimize Spring Beans

Lazy‑loading beans can further improve startup speed.

@Component
@Lazy
public class HeavyService {
    // ...
}
// The @Lazy annotation delays bean creation until first use.

8. JIT Compilation Tuning

Adjusting the JIT compiler can reduce compilation overhead.

java -XX:TieredStopAtLevel=1 -jar myapp.jar
// Stops JIT compilation at tier 1, speeding up startup.

9. Reduce Classpath Scanning

Limiting the packages scanned by Spring Boot cuts down initialization work.

@SpringBootApplication(scanBasePackages = "com.myapp.package1")
public class MyApplication {
    // ...
}
// This restricts the packages Spring Boot scans at startup.

10. Use Spring Boot DevTools Restart Feature

DevTools provides fast restart during development, improving developer productivity.

# application.properties
spring.devtools.restart.enabled=true
// Enables DevTools restart, allowing code changes without a full restart.

By applying these methods—lazy loading, configuration tweaks, dependency pruning, bean optimization, JVM tuning, and development tools—you can noticeably reduce Spring Boot startup time and enhance overall development and deployment efficiency.