SvelteKit 2 vs Leptos
Real-world performance comparison based on identical SaaS dashboard implementations.
SvelteKit 2
VPS
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
VPS (Rust)
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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