SvelteKit 2 vs Leptos

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

SvelteKit 2

SvelteKit 2

VPS

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The official Svelte application framework, combining Svelte's compile-time magic with a powerful routing and rendering system. SvelteKit compiles your components to surgical DOM updates with no virtual DOM overhead. Features file-based routing with layouts, server-side rendering, static prerendering, and streaming. Load functions provide type-safe data loading with automatic request deduplication. Form actions handle progressive enhancement elegantly. SvelteKit apps are remarkably small—the compiler eliminates unused code and the runtime is minimal. Ideal for developers who want React-like DX with significantly better performance characteristics.

Leptos

Leptos

VPS (Rust)

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A full-stack Rust framework using fine-grained reactivity. Leptos compiles to WebAssembly for near-native browser performance, with server functions that run seamlessly on the backend. The framework's signal-based reactivity (similar to SolidJS) enables surgical DOM updates without a virtual DOM. Server functions provide RPC-like calls with full type safety between client and server. Leptos can render on the server and hydrate on the client. For Rust developers, Leptos offers a compelling way to build web applications with the safety and performance guarantees Rust is known for. The learning curve is steep but the results are impressive.

Performance Metrics

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

Metric SvelteKit 2 Leptos Winner
TTFB (p50) 44.55ms 44.85ms ◀
TTFB (p95) 48.19ms 50.07ms ◀
LCP (p50) 82ms 72ms ▶
LCP (p95) 95ms 78.2ms ▶
CLS 0 0 =
TBT 0 ms 0 ms =
LCP → TTFB 175 ms N/A -
LCP → Load Delay 0 ms N/A -
LCP → Load Duration 0 ms N/A -
LCP → Render Delay 523 ms N/A -
Performance Score 98 98 =
SEO Score 83 83 =
Accessibility Score 86 86 =
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 SvelteKit 2 Leptos Winner
Exploration Time 4268ms 3206ms ▶
Exploration Tokens 4454 2884 ▶
Files Examined 12 5 ▶
Validation Accuracy 91% 72% ◀
Time Per File 356ms 641ms ◀
Tokens Per File 3019 4138 ◀
Efficiency Score 28.51 29.54 ▶

LLM Understanding (Claude Haiku 4.5)

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

Metric SvelteKit 2 Leptos Winner
Exploration Time 2252ms 2152ms ▶
Exploration Tokens 4502 2880 ▶
Files Examined 12 5 ▶
Validation Accuracy 82% 61% ◀
Time Per File 188ms 430ms ◀
Tokens Per File 3010 4098 ◀
Efficiency Score 37.63 34.01 ◀

Build Metrics

Metric SvelteKit 2 Leptos Winner
Bundle Size (JS) 176.2KB 1050.2KB ◀
Bundle Size (CSS) 23.6KB 0KB ▶
Build Time 0s 0s =
Dependencies 19 15 ▶

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