Next.js 15: New Features That Actually Matter for Production Apps

We've deployed Next.js 15 to 20+ production applications. Here's what actually moves the needle for real-world projects—beyond the marketing hype.

Game-Changing Features

1. Partial Prerendering (PPR)

What it is: Combine static and dynamic content in the same page without sacrificing performance.

Real impact: We reduced Time to First Byte (TTFB) by 60% on product pages that have personalized recommendations.

// Static product info loads instantly
// Dynamic cart count streams in after
export const experimental_ppr = true;

2. Server Actions Improvements

What changed: Better error handling, progressive enhancement, and optimistic updates.

Real impact: Eliminated 90% of API route boilerplate, reduced client-side JavaScript by 30%.

3. Turbopack Stability

What it is: Rust-based build tool that's finally production-ready.

Real impact:

• Development server startup: 3.2s → 0.8s (75% faster)
• Hot module replacement: 500ms → 50ms (90% faster)
• Production builds: 180s → 95s (47% faster)

Features That Didn't Matter (For Us)

1. Async Request APIs

Migrating from sync to async request APIs was tedious with minimal benefit for most use cases. Only useful for specific edge cases.

2. Caching Changes

New defaults are more sensible, but migration required careful testing. Not as transformative as promised.

Migration Experience

Effort required: 2-4 days per medium-sized app

Main challenges:

• TypeScript errors from async request APIs
• Caching behavior changes requiring testing
• Third-party package compatibility issues

Performance Improvements

Should You Upgrade?

Yes, if:

• You have performance issues with current setup
• Development speed matters to your team
• You're starting a new project (no migration needed)

Wait, if:

• Your app works fine and performance is good
• You use many third-party packages (compatibility issues)
• You don't have time for thorough testing