Running a Spring Boot application in Spring Boot - Performance & Optimization

Performance: Running a Spring Boot application

MEDIUM IMPACT

This affects the startup time and initial responsiveness of the web application.

Starting a Spring Boot application for web service

Spring Boot

public static void main(String[] args) {
    SpringApplication app = new SpringApplication(Application.class);
    app.setLazyInitialization(true);
    app.run(args);
}

Enables lazy initialization to delay bean creation until needed, reducing startup time.

📈 Performance Gainreduces startup blocking by up to 30-50%

Starting a Spring Boot application for web service

Spring Boot

public static void main(String[] args) {
    SpringApplication.run(Application.class, args);
}

Starting with default settings loads all beans and auto-configurations eagerly, causing slower startup.

📉 Performance Costblocks startup for 3-5 seconds depending on app size

Performance Comparison

Pattern	Startup Time	Memory Usage	Responsiveness	Verdict
Default eager startup	3-5 seconds	High	Delayed initial response	[X] Bad
Lazy initialization enabled	1.5-3 seconds	Moderate	Faster initial response	[OK] Good

Rendering Pipeline

When running a Spring Boot app, the JVM loads classes, initializes beans, and starts embedded server before serving requests.

→Class Loading

→Bean Initialization

→Embedded Server Startup

⚠️ BottleneckBean Initialization is most expensive due to eager loading of many components.

Core Web Vital Affected

LCP

This affects the startup time and initial responsiveness of the web application.

Optimization Tips

1Enable lazy initialization to reduce startup blocking.

2Exclude unused auto-configurations to lower memory and CPU load.

3Use JVM profilers to identify slow bean initializations.

Performance Quiz - 3 Questions

What is the main cause of slow startup in a Spring Boot application?

A Large HTML files served

B Eager loading of all beans and auto-configurations

C Slow network connection

D Too many HTTP requests

DevTools: Spring Boot Actuator and JVM Profilers

How to check: Enable Spring Boot Actuator and use JVM profilers like VisualVM to monitor startup phases and bean loading times.

What to look for: Look for long bean initialization times and high CPU usage during startup to identify bottlenecks.