Grouping APIs by tags in Spring Boot - Performance & Optimization

Performance: Grouping APIs by tags

MEDIUM IMPACT

This affects the API documentation load time and client-side rendering speed when browsing grouped endpoints.

Organizing API endpoints in documentation for faster client rendering

Spring Boot

@RestController
@RequestMapping("/api/users")
@Tag(name = "Users", description = "User management APIs")
public class UserController {
  @GetMapping("")
  public List<User> getUsers() { ... }
  @PostMapping("")
  public User createUser() { ... }
}

@RestController
@RequestMapping("/api/orders")
@Tag(name = "Orders", description = "Order management APIs")
public class OrderController {
  @GetMapping("")
  public List<Order> getOrders() { ... }
}

Endpoints are grouped by tags, so documentation UI renders smaller groups on demand, improving load speed and user navigation.

📈 Performance GainReduces initial DOM nodes rendered, improving LCP and interaction readiness.

Organizing API endpoints in documentation for faster client rendering

Spring Boot

@RestController
@RequestMapping("/api")
public class UserController {
  @GetMapping("/users")
  public List<User> getUsers() { ... }
  @PostMapping("/users")
  public User createUser() { ... }
  @GetMapping("/orders")
  public List<Order> getOrders() { ... }
}

All endpoints are in one controller without tags, causing documentation UI to render a long flat list, slowing initial load and navigation.

📉 Performance CostDocumentation UI triggers rendering of all endpoints at once, increasing LCP and blocking user interaction.

Performance Comparison

Pattern	DOM Operations	Reflows	Paint Cost	Verdict
Flat list of all endpoints	High number of DOM nodes	Multiple reflows due to large layout	High paint cost from many elements	[X] Bad
Grouped endpoints by tags	Fewer DOM nodes initially	Single reflow per group expansion	Lower paint cost with smaller visible sets	[OK] Good

Rendering Pipeline

Grouping APIs by tags reduces the number of DOM nodes rendered initially by the documentation UI, lowering the cost in style calculation, layout, and paint stages.

→DOM Construction

→Style Calculation

→Layout

→Paint

⚠️ BottleneckLayout and Paint stages due to large flat lists of endpoints

Core Web Vital Affected

LCP

This affects the API documentation load time and client-side rendering speed when browsing grouped endpoints.

Optimization Tips

1Group API endpoints by tags to reduce initial DOM size in documentation UI.

2Avoid rendering all endpoints at once to prevent layout thrashing and slow paint.

3Use lazy loading or collapsible groups to improve user interaction speed.

Performance Quiz - 3 Questions

How does grouping APIs by tags affect the documentation page's Largest Contentful Paint (LCP)?

A It reduces LCP by limiting initial DOM nodes rendered

B It increases LCP by adding extra grouping elements

C It has no effect on LCP

D It only affects interaction speed, not LCP

DevTools: Performance

How to check: Record a performance profile while opening the API documentation page and expanding groups. Observe the flame chart for layout and paint times.

What to look for: Look for long layout and paint tasks when all endpoints render at once versus shorter tasks when grouped and lazily loaded.