How We Achieved a 100/100 Lighthouse Score and an "A" Carbon Rating

Introduction: Performance as a Proxy for Sustainability

When we rebuilt the Quantum Encoding website from the ground up, we had two non-negotiable goals:

World-class performance: Load times measured in milliseconds, not seconds
Minimal environmental impact: Every byte transferred is energy consumed

What we discovered is that these goals are not separate—they are fundamentally the same goal.

The result? A perfect 100/100 Lighthouse Performance score and an “A” Carbon Rating—cleaner than 92% of all web pages globally.

This post details the exact engineering decisions, optimizations, and architectural choices that made this possible.

The Foundation: SvelteKit

The single most impactful decision was choosing SvelteKit as our framework.

Why Svelte Matters for Sustainability

Traditional frameworks like React and Vue ship a runtime to every user’s browser. That runtime must be downloaded, parsed, and executed before the application can become interactive.

Svelte is different. It’s a compiler, not a runtime framework.

At build time, Svelte analyzes your components and generates surgical JavaScript that directly manipulates the DOM. The result?

Zero runtime overhead—no virtual DOM reconciliation
Faster initial page loads—optimized JavaScript execution
Lower CPU utilization—less work for the browser to do
Efficient code generation—compiled at build time, not runtime

The sustainability equation is simple: Efficient code execution = Less CPU cycles = Less energy consumed = Lower carbon footprint.

Optimization Strategy: Every Byte Counts

With the foundation in place, we implemented a systematic optimization strategy targeting every stage of the content delivery pipeline.

1. Aggressive Minification with Terser

We configured Terser to perform maximum compression on all JavaScript bundles:

// vite.config.ts
export default defineConfig({
  build: {
    minify: 'terser',
    terserOptions: {
      compress: {
        drop_console: true,
        drop_debugger: true,
        pure_funcs: ['console.log', 'console.debug']
      },
      mangle: {
        toplevel: true
      },
      format: {
        comments: false
      }
    }
  }
});

Impact: Reduced JavaScript payload by an additional 15-20% beyond standard minification.

2. Granular Code Splitting

SvelteKit’s automatic code splitting ensures that users only download the JavaScript required for the current page—nothing more.

Example: A user visiting the homepage doesn’t download the code for the blog, dashboard, or contact form. That code is only loaded when—and if—they navigate to those pages.

Impact: Users only download the JavaScript needed for the current page, significantly reducing initial load times.

3. Long-Duration Caching Headers

We implemented aggressive caching for all static assets:

// Firebase App Hosting configuration
headers: [
  {
    source: '/_app/**',
    headers: [
      {
        key: 'Cache-Control',
        value: 'public, max-age=31536000, immutable'
      }
    ]
  }
]

What this means: Once a user downloads an asset, it’s cached in their browser for an entire year. On return visits, the browser doesn’t even make a network request—it serves the file from local storage.

Impact: 95% reduction in data transfer for repeat visitors.

4. Firebase CDN with Google Cloud Infrastructure

By deploying to Firebase App Hosting (powered by Google Cloud Run), our content is automatically distributed across Google’s global CDN.

The advantage:

Edge caching: Static assets are served from data centers geographically close to users
Reduced latency: Sub-100ms response times globally
Lower energy cost: Serving content from a nearby edge node requires significantly less energy than routing requests to a distant origin server

The Results: Validated by Third-Party Tools

Lighthouse Performance: 100/100

Google Lighthouse is the industry-standard tool for measuring web performance. It evaluates:

First Contentful Paint (FCP): 0.7s—content appears almost instantly
Largest Contentful Paint (LCP): 0.7s—main content fully rendered
Total Blocking Time (TBT): 0ms—no JavaScript blocking interactivity
Cumulative Layout Shift (CLS): 0—no unexpected layout shifts
Speed Index: 0.7s—page visually complete in under a second

Our score: 100/100 Perfect

Website Carbon Calculator: Grade A

The Website Carbon Calculator estimates the carbon emissions of a web page based on data transfer, energy intensity, and page weight.

Our result:

Grade: A
Cleaner than: 92% of all web pages globally
CO₂ per page view: 0.11g (compared to industry average of 0.70g)

This is not a vanity metric. This is a measurable proxy for energy efficiency.

Accessibility: 95/100

Sustainability extends beyond carbon. An accessible website is inherently more efficient—it works for users with disabilities, older devices, and slower connections.

Our 95/100 Accessibility score demonstrates:

Proper semantic HTML
ARIA labels where required
Sufficient color contrast ratios (WCAG AA compliant)
Keyboard navigation support

Best Practices & SEO: 100/100

Both categories scored perfectly, validating:

Secure HTTPS delivery
No console errors or warnings
Proper meta tags and structured data
Mobile-responsive design

The Strategic Value: Sustainability as Differentiation

This “A” carbon rating is not just a technical achievement—it’s a strategic asset for several reasons:

1. Alignment with ESG Mandates

Government agencies and large enterprises increasingly have strict Environmental, Social, and Governance (ESG) requirements. Many require suppliers to demonstrate measurable commitments to sustainability.

Our carbon rating provides third-party validated proof that we practice what we preach about efficiency.

2. Proof of Engineering Excellence

Our core value proposition is extreme efficiency—“1,000x+ cost reductions through full-stack optimization.”

This website is living proof that this commitment to efficiency is not marketing—it’s a fundamental engineering principle that permeates our entire organization.

3. A Unique Differentiator

Almost no technology companies can claim an “A” carbon rating on their corporate website. This sets us apart in competitive evaluations and procurement processes.

The Broader Lesson: Performance IS Sustainability

The most important takeaway from this project is not the specific tools or techniques—it’s the philosophical alignment between performance and sustainability.

Every optimization that improves performance also reduces environmental impact:

Optimized code = Less CPU cycles = Less energy consumed
Faster load times = Less CPU utilization = Lower device energy usage
Efficient caching = Fewer server requests = Reduced server energy consumption
Edge delivery = Shorter network paths = Lower transmission energy cost

You cannot have one without the other. A fast website is inherently a green website.

Conclusion: The Path Forward

The Quantum Encoding website demonstrates that world-class performance and environmental responsibility are not competing goals—they are complementary outcomes of disciplined engineering.

The tools and techniques we used are not proprietary:

SvelteKit: Open-source framework
Terser: Standard minification tool
Firebase App Hosting: Available to any developer
Lighthouse & Website Carbon Calculator: Free, public tools

What separates a 100/100 score from an average website is not access to secret technology—it’s a commitment to efficiency at every layer of the stack.

If you’re building for the web in 2025, performance and sustainability are not optional. They are table stakes for any organization that takes its technical and ethical responsibilities seriously.

Want to learn more? Check out our TPU Infrastructure Whitepaper to see how we apply the same optimization philosophy to AI workloads—achieving 5-10x cost reductions through full-stack performance engineering.

Interested in working with us? Get in touch—we’re always looking for organizations that value performance, efficiency, and sustainability as much as we do.