React Router v7 vs Fastify + React

Real-world performance comparison based on identical SaaS dashboard implementations.

React Router v7

React Router v7

VPS

View Live Demo

The official React routing library, now evolved into a full-stack framework. React Router v7 represents the merger with Remix, bringing data loading patterns that eliminate waterfalls and keep your UI in sync with your URLs. Loaders fetch data before rendering, actions handle mutations, and the router manages pending/optimistic states automatically. Nested routes enable parallel data loading and isolated error boundaries. Type-safe links catch broken routes at build time. Compared to Next.js, React Router offers a more explicit data flow with loaders/actions and tighter Remix-style conventions. It's particularly strong for apps with complex forms and frequent user interactions.

Fastify + React

Fastify + React

VPS

View Live Demo

Node.js high-performance web framework combined with React SSR. Fastify is one of the fastest Node.js frameworks, built on a robust plugin architecture with JSON Schema validation and automatic OpenAPI documentation. This implementation uses Fastify as the server with custom React SSR integration. Fastify's encapsulation model keeps plugins isolated, while hooks provide fine-grained request lifecycle control. Ideal for teams with existing Node.js/Express experience who want better performance and structure. Fastify's plugin ecosystem covers everything from rate limiting to WebSocket support.

Performance Metrics

Lower is better for all metrics. Green indicates the faster framework.

Metric React Router v7 Fastify + React Winner
TTFB (p50) 50.2ms 42.95ms ▶
TTFB (p95) 51.55ms 46.06ms ▶
LCP (p50) 80ms 70ms ▶
LCP (p95) 86.2ms 78.2ms ▶
CLS 0 0 =
TBT 0 ms 0 ms =
LCP → TTFB N/A N/A -
LCP → Load Delay N/A N/A -
LCP → Load Duration N/A N/A -
LCP → Render Delay N/A N/A -
Performance Score 98 99 ▶
SEO Score 83 92 ▶
Accessibility Score 80 80 =
Best Practices Score 100 100 =

LLM Understanding (Claude Opus 4.5)

How efficiently Claude Opus 4.5 understands the codebase. Based on exploration + validation tests.

Metric React Router v7 Fastify + React Winner
Exploration Time 3232ms 3580ms ◀
Exploration Tokens 2623 3244 ◀
Files Examined 8 10 ◀
Validation Accuracy 73% 80% ▶
Time Per File 404ms 358ms ▶
Tokens Per File 2954 3060 ◀
Efficiency Score 25.65 27.95 ▶

LLM Understanding (Claude Haiku 4.5)

How efficiently Claude Haiku 4.5 understands the codebase. Based on exploration + validation tests.

Metric React Router v7 Fastify + React Winner
Exploration Time 3285ms 1869ms ▶
Exploration Tokens 2751 3278 ◀
Files Examined 8 10 ◀
Validation Accuracy 67% 68% ▶
Time Per File 411ms 187ms ▶
Tokens Per File 2969 3061 ◀
Efficiency Score 19.22 26.22 ▶

Build Metrics

Metric React Router v7 Fastify + React Winner
Bundle Size (JS) 462.3KB 283.6KB ▶
Bundle Size (CSS) 23.3KB 23.1KB ▶
Build Time 0s 0s =
Dependencies 22 21 ▶

Want to see more framework comparisons?

View All Comparisons