Elysia + React vs Fastify + React

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

Elysia + React

Elysia + React

VPS (Bun)

View Live Demo

A Bun-native server framework paired with React for SSR. Elysia leverages Bun's speed and provides end-to-end type safety through its innovative "Eden" client that infers types directly from your API routes. Elysia's declarative syntax is reminiscent of tRPC but with full HTTP control. Plugins handle validation, authentication, and documentation generation. The framework achieves exceptional throughput on the Bun runtime. This stack demonstrates what's possible when you combine Bun's performance with a thoughtfully designed type-safe server framework and React's component model.

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 Elysia + React Fastify + React Winner
TTFB (p50) 44.75ms 42.95ms ▶
TTFB (p95) 50.52ms 46.06ms ▶
LCP (p50) 72ms 70ms ▶
LCP (p95) 84ms 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 100 99 ◀
SEO Score 92 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 Elysia + React Fastify + React Winner
Exploration Time 3484ms 3580ms ◀
Exploration Tokens 3402 3244 ▶
Files Examined 10 10 =
Validation Accuracy 74% 80% ▶
Time Per File 348ms 358ms ◀
Tokens Per File 3070 3060 ▶
Efficiency Score 23.18 27.95 ▶

LLM Understanding (Claude Haiku 4.5)

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

Metric Elysia + React Fastify + React Winner
Exploration Time 2400ms 1869ms ▶
Exploration Tokens 3430 3278 ▶
Files Examined 10 10 =
Validation Accuracy 63% 68% ▶
Time Per File 240ms 187ms ▶
Tokens Per File 3060 3061 ◀
Efficiency Score 15.01 26.22 ▶

Build Metrics

Metric Elysia + React Fastify + React Winner
Bundle Size (JS) 283.6KB 283.6KB =
Bundle Size (CSS) 23.1KB 23.1KB =
Build Time 0s 0s =
Dependencies 20 21 ◀

Want to see more framework comparisons?

View All Comparisons