Case study: rebuilding mod585.com from Lighthouse 82 to 94

In April 2026 we cut over www.mod585.com from a Shape A monorepo subdir to a Shape B repo-per-site. The same deploy hash served both the apex domain and the Vercel alias byte-for-byte — zero downtime, zero traffic loss. The reason for the rebuild was not the layout: the v1 layout still works. The reason was Lighthouse Performance on mobile, which had drifted to 82.

What moved the score

Three changes carried the bulk of the +12 lift: switching the logo to a properly-sized priority image, eliminating a layout-shift in the footer that was costing us CLS on every page load, and removing a JavaScript animation runtime that was fighting the browser for paint time. None of these were visible to the user. All three were measurable.

Why we tell this story

Most agencies will not show you a before-and-after Lighthouse score because they do not measure. We measure on every deploy. If your site is in the 40s on mobile, you are leaving search traffic on the table — and your visitors are bouncing before the page paints. The fix is rarely glamorous. It is mostly about removing things, not adding them.