Shopify
A Performance Budget That Survives Contact With a Real Store
Performance work that is not enforced gets undone within a quarter. Here is the budget I use, the numbers behind each limit, and how to fail a build on it.
Shopify
Your Theme Has 340 Settings and Merchants Use Eleven of Them
Every setting is a conditional in Liquid, a branch in CSS and a support question. I counted what a real theme actually used, and the answer changed how I…
Shopify
The Theme JavaScript That Blocked Rendering for 1.2 Seconds
One script tag without defer, loading a bundle nothing above the fold needed. How to find what is blocking your paint and what each fix actually changes.
Shopify
The Announcement Bar That Cost 0.31 CLS
Every element on the page moved down 44 pixels, a third of a second after paint. Finding the culprit took one API and a screen recording.
Shopify
How to Tell Which App Is Actually Slowing Your Store Down
Uninstalling apps one at a time and re-running Lighthouse is not a method. Here is how to attribute main thread time and bytes to a specific app in one pass.
Shopify
Your Lazy-Loaded Hero Image Is Why LCP Is Four Seconds
Someone added loading lazy to every image in the theme, including the one the browser needs first. Here is how the biggest LCP regression I have seen was…
DevOps
The Rollback That the CDN Kept Serving for an Hour
The deploy was reverted in four minutes, and the incident lasted an hour, because the edge cache held the broken build and kept serving it to everyone the…
Performance
The Token Bill Is a Performance Metric, and Yours Is Unread
The invoice tripled with no traffic change, because the prompts tripled, and nobody was reading tokens as a metric.
Shopify
You Are Serving a 2400px Image to a 390px Phone
The srcset was correct and the browser still downloaded the largest file. The sizes attribute was lying, and almost every theme I audit gets it wrong.
Performance
Your RAG Is Slow Because Retrieval Is an Untuned Database
The LLM answered in four hundred milliseconds and the request took four seconds. The gap was retrieval, a vector search over an index nobody sized, chunked…
Shopify
The Price That Changed by a Cent in Every Other Market
The converted price looked right on the product page and wrong on the invoice, by a cent, in every market but the home one.
Performance
The Query That Was Fast for Two Years and Then Was Not
Nothing about the query changed. The table crossed the size where the planner stops choosing the index and starts scanning, because the working set stopped…