Next.js 16 vs Astro 5

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

Next.js 16

Next.js 16

VPS (Bun)

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The React meta-framework running on Bun runtime. Built by Vercel, Next.js supports SSR, SSG, ISR, and streaming—all configured per-route. This variant uses Bun runtime for potentially faster startup times and request handling. The App Router architecture brings React Server Components, nested layouts, and Server Actions. While Bun support for Next.js is unofficial, it works in practice and offers a comparison point for runtime performance. Ideal for teams wanting to benchmark Node.js vs Bun performance with their Next.js applications.

Astro 5

Astro 5

VPS

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The web framework for content-driven websites. Astro's revolutionary Islands architecture ships zero JavaScript by default—interactive components hydrate independently only where needed, dramatically reducing bundle sizes. Astro 5 introduces Content Layer for type-safe content collections, Server Islands for mixing static and dynamic content, and improved build performance. The framework is UI-agnostic: use React, Vue, Svelte, Solid, or vanilla JS components in the same project. Perfect for marketing sites, documentation, blogs, and any content-heavy application where performance matters. Astro consistently achieves perfect Lighthouse scores with minimal effort.

Performance Metrics

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

Metric Next.js 16 Astro 5 Winner
TTFB (p50) 0ms 50.5ms ◀
TTFB (p95) 0ms 52.23ms ◀
LCP (p50) 0ms 80ms ◀
LCP (p95) 0ms 86.2ms ◀
CLS 0 0 =
TBT N/A 0 ms -
LCP → TTFB N/A 214 ms -
LCP → Load Delay N/A 0 ms -
LCP → Load Duration N/A 0 ms -
LCP → Render Delay N/A 535 ms -
Performance Score N/A 99 -
SEO Score N/A 92 -
Accessibility Score N/A 79 -
Best Practices Score N/A 100 -

LLM Understanding (Claude Opus 4.5)

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

Metric Next.js 16 Astro 5 Winner
Exploration Time N/A 3955ms -
Exploration Tokens N/A 2756 -
Files Examined N/A 8 -
Validation Accuracy N/A 86% -
Time Per File N/A 494ms -
Tokens Per File N/A 3496 -
Efficiency Score N/A 33.49 -

LLM Understanding (Claude Haiku 4.5)

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

Metric Next.js 16 Astro 5 Winner
Exploration Time N/A 2240ms -
Exploration Tokens N/A 2764 -
Files Examined N/A 8 -
Validation Accuracy N/A 81% -
Time Per File N/A 280ms -
Tokens Per File N/A 3474 -
Efficiency Score N/A 49.18 -

Build Metrics

Metric Next.js 16 Astro 5 Winner
Bundle Size (JS) 642.6KB 242.7KB ▶
Bundle Size (CSS) 23.4KB 22.6KB ▶
Build Time 0s 0s =
Dependencies 19 18 ▶

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