speedrun.a16z.com

The numbers

First visit

3.37 g CO₂e

Return visit

2.34 g CO₂e

Hosting

unknown

LCP

248 ms

CLS

n/a

TTFB

6 ms

At 10,000 views a month this page emits about 373.0 kg CO₂e a year, roughly 1529 km in an average petrol car. The estimate assumes 75% new and 25% returning visitors, a measured cache reload ratio of 69%, and world-average grid intensity. How we calculate this

1. Audit third-party servicessave ~1.32 g/visit (9.65 MB)High impact · moderate effort

   15 third-party domains account for 19.56 MB (86% of the page).

   Remove services that no longer earn their place; load the rest on interaction (facades for embeds, delayed consent-gated tags). Each third party is also a privacy and performance dependency.

   • vod-adaptive-ak.vimeocdn.com15.73 MB
   • substackcdn.com3.12 MB
   • f.vimeocdn.com348 kB
   • www.googletagmanager.com300 kB
   • speedrun.substack.com31 kB
   • substack.com14 kB

   WSG 3.5: Treat third parties the same as first parties
2. Serve images at the size they displaysave ~0.166 g/visit (1.21 MB)High impact · quick fix

   12 images are encoded at more than twice the pixels the layout shows, even accounting for this viewport's pixel density.

   Generate multiple sizes and let the browser pick with srcset/sizes; a 4000px original behind a 400px slot spends bandwidth no screen displays.

   • image428 kB
   • image306 kB
   • image205 kB
   • image205 kB
   • image144 kB

   WSG 2.9: Optimize media to reduce resource use
3. Reduce JavaScript payloadsave ~0.140 g/visit (1.02 MB)High impact · moderate effort

   215 scripts total 4.10 MB on the wire (13.03 MB decoded). Bundles this size usually carry a lot of unused code.

   Split bundles per route, tree-shake dependencies, and audit with a bundle analyzer or coverage profile. A 25% cut is a conservative target for bundles this size.

   • _app-96134cb456a3216c.js680 kB
   • player.module.js226 kB
   • js170 kB
   • 49085.add84692.js136 kB
   • gtm.js131 kB

   WSG 3.2: Minify and remove unused codeWSG 3.3: Modularize bandwidth-heavy components
4. Replace heavyweight GIFssave ~0.044 g/visit (320 kB)High impact · quick fix

   1 GIF totals 376 kB. GIF is the least efficient image format still in common use, animated or not.

   If it animates, re-encode the clip as a muted looping MP4 or WebM (typically a 10x reduction); if it is a still, convert it to WebP or AVIF.

   • https%3A%2F%2Fsubstack-post-media.s3.amazonaw…376 kB

   WSG 2.9: Optimize media to reduce resource use
5. Convert and compress imagessave ~0.030 g/visit (217 kB)Medium impact · quick fix

   2 images exceed 300 kB apiece.

   Serve AVIF (or WebP) with responsive srcset sizes, and re-compress oversized files. AVIF typically halves JPEG weight at the same visual quality.

   • image428 kB
   • image306 kB

   WSG 2.9: Optimize media to reduce resource use
6. Verify your hosting energyMedium impact · moderate effort

   This host has not published renewable energy evidence with the Green Web Foundation, so its energy source is unknown.

   Choose a provider listed in the Green Web Directory, or ask your current provider to publish evidence (and a carbon.txt). This cuts the data-center share of every single page view.

   • carbon.txtNo carbon.txt found at the site root; publishing one is the lightest first step.

   WSG 4.1: Use sustainable hosting
7. Upgrade compression beyond gzipsave ~0.054 g/visit (393 kB)Advisory · quick fix

   2.62 MB of text ships gzip-compressed; Brotli or Zstandard would cut roughly another 15-20%, and browsers without them fall back to gzip automatically.

   Serve precompressed Brotli for static text assets (highest level, compressed at build time) and enable Brotli or zstd for dynamic responses; keep gzip only as the fallback.

   • 49085.add84692.js136 kB
   • 65126.e7b55b14.js124 kB
   • 68455.b640be8a.js93 kB
   • 86696.e7a14d3d.js89 kB
   • 14979.e99ca01f.js73 kB

   WSG 4.3: Reduce data transfer with compression
8. Optimize web fontssave ~0.011 g/visit (77 kB)Advisory · quick fix

   6 font files total 220 kB.

   Subset fonts to used glyphs, prefer one variable font over multiple weights, serve WOFF2 only, and consider system fonts for UI text.

   • 64c1c31384189284-s.p.woff237 kB
   • 3d660e1dc7b780d4-s.p.woff237 kB
   • 8eb8b7822da4764a-s.p.woff237 kB
   • dc72bb61e9fdf7fa-s.p.woff237 kB
   • c062731b6932ef63-s.p.woff236 kB

   WSG 2.11: Use optimized web typography
9. Stop downloading the same asset twicesave ~0.010 g/visit (73 kB)Advisory · quick fix

   11 assets were fetched more than once in a single page load (98 kB of repeated transfer).

   Usually a script injected twice or cache-busting query strings that differ per reference. Load each asset once and let the HTTP cache do its job.

   • 2753-56819a94430996c9.js2 downloads · 30 kB
   • 8896-2541b0b8ff2d13f1.js2 downloads · 7.6 kB
   • 8583-bcaaffd8cabf6a69.js2 downloads · 12 kB
   • 5510-bbd88db9c6107c0b.js2 downloads · 12 kB
   • apply-aeab4bcb0323888b.js2 downloads · 2.1 kB

   WSG 3.2: Minify and remove unused code
10. Remove references to broken resourcessave ~<0.001 g/visit (877 B)Advisory · quick fix

    2 requests answered 4xx/5xx on load: transfer and connections spent on nothing, on every single visit.

    Delete or fix the references (stale asset URLs, dead third-party tags). Each one is a request the page provably does not need.

    • meHTTP 401 · 227 B
    • flowsHTTP 401 · 1.3 kB

    WSG 4.4: Setup necessary error pages and redirection links
11. Set a page-weight budgetAdvisory · moderate effort

    At 22.71 MB per view this page rates F. The findings above list where the weight is.

    Agree a transfer budget (e.g. under 975 kB reaches a B), enforce it in CI, and re-scan after each change to hold the line.

    WSG 3.1: Set goals based on performance and energy impact

Where the bytes are

• Data (XHR)15.73 MB · 14 req
• JavaScript4.10 MB · 215 req
• Images2.21 MB · 20 req
• CSS278 kB · 25 req
• Fonts220 kB · 6 req
• Other98 kB · 19 req
• HTML48 kB · 4 req
• Data (fetch)25 kB · 12 req