Conditional bean creation in Spring Boot - Performance & Optimization

Performance: Conditional bean creation

MEDIUM IMPACT

This affects application startup time and memory usage by controlling which beans are created and loaded into the Spring context.

Creating beans only when certain conditions are met to optimize startup performance

Spring Boot

@Bean
@ConditionalOnProperty(name = "feature.serviceA.enabled", havingValue = "true")
public ServiceA serviceA() {
  return new ServiceA();
}

@Bean
@ConditionalOnProperty(name = "feature.serviceB.enabled", havingValue = "true")
public ServiceB serviceB() {
  return new ServiceB();
}

Beans are created only if the related feature flag is enabled, reducing startup overhead.

📈 Performance GainReduces startup time and memory usage by skipping unnecessary bean creation.

Creating beans only when certain conditions are met to optimize startup performance

Spring Boot

@Bean
public ServiceA serviceA() {
  return new ServiceA();
}

@Bean
public ServiceB serviceB() {
  return new ServiceB();
}

All beans are created regardless of whether they are needed, increasing startup time and memory use.

📉 Performance CostIncreases startup time by creating unnecessary beans and uses more memory.

Performance Comparison

Pattern	Beans Created	Startup Time Impact	Memory Usage	Verdict
Unconditional bean creation	All beans	High - creates all beans regardless of need	High - all beans consume memory	[X] Bad
Conditional bean creation	Only needed beans	Low - skips unnecessary beans	Low - less memory used	[OK] Good

Rendering Pipeline

During application startup, Spring evaluates conditions before creating beans, affecting the initialization phase but not runtime rendering.

→Bean Initialization

→Application Context Setup

⚠️ BottleneckBean Initialization stage can be slowed by creating unnecessary beans.

Optimization Tips

1Use conditional annotations to create beans only when needed.

2Avoid creating all beans unconditionally to reduce startup time.

3Check bean creation logs to verify conditional loading.

Performance Quiz - 3 Questions

What is the main performance benefit of using conditional bean creation in Spring Boot?

A Decreases network latency for API calls

B Reduces application startup time by creating only necessary beans

C Improves runtime rendering speed of web pages

D Automatically caches bean results for faster access

DevTools: Spring Boot Actuator / Logs

How to check: Enable debug logging for Spring context startup or use Actuator endpoints to see which beans are loaded.

What to look for: Look for fewer beans initialized and faster startup time in logs or Actuator metrics.