POM.xml and dependencies in Spring Boot - Performance & Optimization

Performance: POM.xml and dependencies

MEDIUM IMPACT

This affects the initial page load speed and overall application startup time by controlling which libraries and their versions are included in the build.

Managing project dependencies for a Spring Boot application

Spring Boot

<dependencies>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
  <!-- Only essential dependencies included -->
</dependencies>

Only essential dependencies are included, reducing bundle size and improving startup speed.

📈 Performance GainSaves 400kb+ in bundle size, reduces startup time by 150-250ms

Managing project dependencies for a Spring Boot application

Spring Boot

<dependencies>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
  </dependency>
  <dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <scope>provided</scope>
  </dependency>
  <dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
  </dependency>
  <!-- Many unused dependencies -->
</dependencies>

Including many unused or unnecessary dependencies increases the final application size and startup time, causing slower page load and higher memory use.

📉 Performance CostAdds 500kb+ to bundle size, increases startup time by 200-300ms

Performance Comparison

Pattern	Bundle Size Impact	Startup Time	Network Load	Verdict
Many unused dependencies	Large (+500kb)	Slow (+200ms)	High	[X] Bad
Minimal essential dependencies	Small (+100kb)	Fast (+50ms)	Low	[OK] Good

Rendering Pipeline

POM.xml dependencies affect the build output size and startup initialization, which indirectly impacts how fast the browser can receive and render the application content.

→Network Transfer

→JavaScript Parsing

→Application Startup

⚠️ BottleneckNetwork Transfer and Application Startup due to larger bundles

Optimization Tips

1Only add dependencies you actually use in your project.

2Avoid duplicate or conflicting dependencies to reduce bundle size.

3Use dependency management to control versions and avoid bloat.

Performance Quiz - 3 Questions

How does including many unused dependencies in POM.xml affect your Spring Boot app?

A Increases bundle size and startup time

B Decreases bundle size

C Improves rendering speed

D Has no effect on performance

DevTools: Network

How to check: Open DevTools, go to Network tab, reload the page, and check the size of JavaScript bundles and load times.

What to look for: Look for large bundle sizes and long load times indicating too many dependencies.