@Configuration and @Bean in Spring Boot - Performance & Optimization

Performance: @Configuration and @Bean

MEDIUM IMPACT

This affects application startup time and memory usage by controlling how beans are created and managed in Spring's container.

Defining reusable service objects in Spring Boot

Spring Boot

@Configuration
public class AppConfig {
  @Bean
  public MyService myService() {
    return new MyService();
  }
}

Explicitly defines singleton bean creation, ensuring only one instance is created and reused.

📈 Performance GainReduces startup time and memory by avoiding duplicate bean instantiation

Defining reusable service objects in Spring Boot

Spring Boot

@Component
@Scope("prototype")
public class MyService {
  // service logic
}

// Multiple instances created if prototype scope or no singleton management

Using @Component with prototype scope can lead to multiple bean instances, increasing memory and startup cost.

📉 Performance CostIncreases memory usage and startup time due to redundant bean creation

Performance Comparison

Pattern	Bean Instances	Startup Time	Memory Usage	Verdict
@Component with prototype scope	Multiple instances possible	Higher due to redundant creation	Higher due to duplicates	[X] Bad
@Configuration with @Bean	Single instance per bean	Lower due to controlled creation	Lower due to reuse	[OK] Good

Rendering Pipeline

Spring processes @Configuration classes during startup to create and register beans in the application context before serving requests.

→Bean Creation

→Dependency Injection

→Application Startup

⚠️ BottleneckBean Creation stage can be slow if many beans are created redundantly or with complex initialization.

Optimization Tips

1Use @Configuration and @Bean to define singleton beans explicitly.

2Avoid multiple bean instances to reduce memory and startup time.

3Monitor bean creation with Spring Boot Actuator and profilers.

Performance Quiz - 3 Questions

What is the main performance benefit of using @Configuration with @Bean in Spring Boot?

A Ensures singleton bean creation reducing memory and startup time

B Automatically caches HTTP responses

C Improves database query speed

D Reduces network latency

DevTools: Spring Boot Actuator and IDE Profiler

How to check: Enable Actuator endpoints and use IDE profiler to monitor bean creation count and memory usage during startup.

What to look for: Look for number of bean instances and startup duration; fewer beans and faster startup indicate better performance.