www.mixedbread.com/blog/toast-1

The numbers

First visit

0.323 g CO₂e

Return visit

0.0080 g CO₂e

Hosting

unknown

LCP

420 ms

CLS

n/a

TTFB

7 ms

At 10,000 views a month this page emits about 29.3 kg CO₂e a year, roughly 120 km in an average petrol car. The estimate assumes 75% new and 25% returning visitors, a measured cache reload ratio of 2%, and world-average grid intensity. How we calculate this

1. Reduce JavaScript payloadsave ~0.048 g/visit (426 kB)High impact · moderate effort

   83 scripts total 1.70 MB on the wire (6.21 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.

   • js190 kB
   • 0o7wzy9q8_irq.js92 kB
   • 0wvv.930xmc4q.js92 kB
   • 15jd7o4cmks-6.js78 kB
   • 0tkavkoufhmxn.js74 kB

   WSG 3.2: Minify and remove unused codeWSG 3.3: Modularize bandwidth-heavy components
2. Audit third-party servicessave ~0.012 g/visit (108 kB)Medium impact · moderate effort

   6 third-party domains account for 215 kB (10% 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.

   • www.googletagmanager.com190 kB
   • app.cal.com24 kB
   • stats.g.doubleclick.net551 B
   • www.google.de408 B
   • 0 B
   • region1.analytics.google.com0 B

   WSG 3.5: Treat third parties the same as first parties
3. Defer video and audioMedium impact · quick fix

   1 video autoplays.

   Never autoload media: use preload="none" with a poster image, load players on interaction, and stream in an efficient codec (AV1/HEVC).

   • demo_video.mp40 B

   WSG 2.9: Optimize media to reduce resource use
4. Serve images at the size they displaysave ~0.0067 g/visit (59 kB)Medium impact · quick fix

   1 image is 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.

   • image101 kB

   WSG 2.9: Optimize media to reduce resource use
5. 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
6. Set a page-weight budgetAdvisory · moderate effort

   At 2.18 MB per view this page rates D. 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

• JavaScript1.70 MB · 83 req
• Data (fetch)157 kB · 51 req
• Images128 kB · 4 req
• Fonts79 kB · 3 req
• CSS57 kB · 4 req
• HTML51 kB · 1 req
• Other551 B · 1 req
• Audio / video0 B · 1 req