Route groups with (groupName) in NextJS - Performance & Optimization

Performance: Route groups with (groupName)

MEDIUM IMPACT

This affects the routing structure's impact on bundle size and initial page load speed by organizing routes without adding extra URL segments.

Organizing routes without affecting URL paths

NextJS

app/(admin)/dashboard/page.tsx
// Using (admin) as a route group keeps URL as /admin/dashboard without /admin prefix

Route groups organize code without adding URL segments, reducing navigation overhead and keeping URLs clean.

📈 Performance GainReduces unnecessary client-side routing steps, improving LCP by a few milliseconds

Organizing routes without affecting URL paths

NextJS

app/admin/dashboard/page.tsx
// Using folders without parentheses adds extra URL segments like /admin/dashboard

This adds extra URL path segments, increasing URL length and potentially triggering more client-side navigation and re-renders.

📉 Performance CostIncreases initial navigation complexity and can add small delays in LCP due to longer URL parsing

Performance Comparison

Pattern	DOM Operations	Reflows	Paint Cost	Verdict
Using folders without groupName (adds URL segments)	No extra DOM nodes	No reflows	Minimal paint cost	[X] Bad
Using route groups with (groupName) to hide folders	No extra DOM nodes	No reflows	Minimal paint cost	[OK] Good

Rendering Pipeline

Route groups affect how Next.js builds the routing tree and bundles code. They do not add extra DOM nodes but influence client-side routing and bundle splitting.

→Bundle Splitting

→Client-side Routing

→Initial Load

⚠️ BottleneckClient-side Routing complexity

Core Web Vital Affected

LCP

This affects the routing structure's impact on bundle size and initial page load speed by organizing routes without adding extra URL segments.

Optimization Tips

1Use route groups to organize routes without adding URL path segments.

2Avoid extra folders in URLs to reduce client-side routing overhead.

3Clean URLs help improve Largest Contentful Paint (LCP) by speeding navigation.

Performance Quiz - 3 Questions

How do route groups with (groupName) affect URL paths in Next.js?

A They remove routes from the app

B They organize routes without adding extra URL segments

C They add extra URL segments for each group

D They increase the number of DOM nodes

DevTools: Performance

How to check: Record a page load and navigation in the Performance panel. Compare the time spent in client-side routing and script evaluation.

What to look for: Look for shorter scripting and routing times when using route groups, indicating faster navigation and load.

Practice

1. What is the main purpose of using route groups with (groupName) in Next.js?

easy

A. To organize routes in folders without changing the URL structure

B. To change the URL path to include the group name

C. To create dynamic routes with parameters

D. To add middleware to specific routes

Solution

1. Step 1: Understand route groups concept

   Route groups use parentheses in folder names to group routes logically without affecting the URL path.

2. Step 2: Compare URL effect

   Since the URL does not include the group name, the main purpose is organization, not URL change.

3. Final Answer:

   To organize routes in folders without changing the URL structure -> Option A

4. Quick Check:

   Route groups = organize without URL change [OK]

Hint: Parentheses folders group routes but keep URLs clean [OK]

Common Mistakes:

• Thinking group name appears in URL
• Confusing with dynamic route parameters
• Assuming it adds middleware automatically

2. Which of the following folder names correctly creates a route group named admin in Next.js?

easy

A. admin

B. (admin)

C. [admin]

D. {admin}

Solution

1. Step 1: Identify route group syntax

   Route groups use parentheses around the folder name, like (groupName).

2. Step 2: Match folder name

   The folder named (admin) correctly creates a route group called admin.

3. Final Answer:

   (admin) -> Option B

4. Quick Check:

   Parentheses folder = route group [OK]

Hint: Use parentheses for route groups, not brackets or braces [OK]

Common Mistakes:

• Using square brackets which are for dynamic routes
• Using curly braces which are invalid
• Omitting parentheses and creating normal folders

3. Given this folder structure in Next.js app router:

app/(dashboard)/page.tsx
app/(dashboard)/settings/page.tsx
app/profile/page.tsx

What URL paths will be available?

medium

A. /, /settings, /profile

B. /(dashboard), /(dashboard)/settings, /profile

C. /dashboard, /dashboard/settings, /profile

D. /dashboard, /settings, /profile

Solution

1. Step 1: Understand route groups effect on URLs

   Folders with parentheses group routes but do not add to URL path.

2. Step 2: Map folder names to URLs

   The (dashboard) group is invisible in URL, so app/(dashboard)/page.tsx maps to / because the page.tsx inside is the root of that group. Similarly, app/(dashboard)/settings/page.tsx maps to /settings. The app/profile/page.tsx maps to /profile.

3. Final Answer:

   /, /settings, /profile -> Option D

4. Quick Check:

   Route groups hide folder name but keep nested paths [OK]

Hint: Route groups hide folder name but keep nested routes [OK]

Common Mistakes:

• Including parentheses folder name in URL
• Ignoring nested folder names inside groups
• Assuming root group maps to root URL

4. You created a folder named (admin) inside app but your routes under it are not working. What is the most likely mistake?

medium

A. You forgot to add a page.tsx file inside the (admin) folder

B. You used square brackets instead of parentheses for the folder name

C. You named the folder admin without parentheses

D. You placed the (admin) folder outside the app directory

Solution

1. Step 1: Check route group folder requirements

   Route groups require a page.tsx or similar file inside to define the route component.

2. Step 2: Identify missing page file issue

   If routes inside (admin) don't work, missing page.tsx is the most common cause.

3. Final Answer:

   You forgot to add a page.tsx file inside the (admin) folder -> Option A

4. Quick Check:

   Missing page.tsx = no route rendered [OK]

Hint: Always add page.tsx inside route group folders [OK]

Common Mistakes:

• Confusing folder naming syntax
• Placing folders outside app directory
• Assuming route groups auto-create pages

5. You want to create two separate route groups (marketing) and (sales) inside app with pages home.tsx and contact.tsx each. How should you organize folders so URLs are /home and /contact without group names in URL?

hard

A. app/(marketing)/home.tsx and app/(sales)/contact/page.tsx

B. app/(marketing)/home.tsx and app/(marketing)/(sales)/contact.tsx

C. app/(marketing)/home.tsx and app/(sales)/contact.tsx

D. app/home.tsx and app/contact.tsx

Solution

1. Step 1: Use route groups to hide folder names

   Folders named with parentheses group routes without adding to URL path.

2. Step 2: Place pages inside separate route groups

   Placing home.tsx inside (marketing) and contact.tsx inside (sales) keeps URLs as /home and /contact.

3. Final Answer:

   app/(marketing)/home.tsx and app/(sales)/contact.tsx -> Option C

4. Quick Check:

   Separate groups hide folder names, URLs stay clean [OK]

Hint: Put pages inside separate parentheses folders for clean URLs [OK]

Common Mistakes:

• Nesting groups causing longer URLs
• Placing pages outside groups losing organization
• Using page.tsx inconsistently inside groups