Performance Engineering
Fast is a budget you enforce, not a score you screenshot.
Core Web Vitals brought inside Google's thresholds on real devices, and kept there by a gate in your pipeline.
The score that was green at launch
Most performance work is done once, screenshotted, and then undone over eighteen months by a marketing tag here, a hero video there, and a font that was only meant to be temporary. The site is not slow because nobody optimized it. It is slow because nothing stopped it drifting back.
Meanwhile the measurement most teams look at is a lab score from a fast machine on a fast connection. Google ranks on field data from real users on real devices, and the gap between the two is where the surprise lives.
We treat performance as a budget with a gate: numbers that must hold, enforced in the pipeline, on the devices your visitors actually use.
What we do
- Core Web Vitals remediation
- LCP, INP and CLS diagnosed from field data and fixed at the cause: render-blocking chains, layout instability, main-thread contention and hydration cost.
- Edge rendering & CDN strategy
- Content served from close to the user, with the right rendering mode per route — static, streamed, or dynamic at the edge — rather than one strategy imposed on the whole site.
- Caching architecture
- Cache layers, invalidation rules and stale-while-revalidate policy designed so speed does not come at the price of stale prices, stock levels or content.
- Image & font pipelines
- Modern formats, correct sizing, priority hints for the largest element, and font loading that does not shift the layout after paint.
- JavaScript budget & code splitting
- A hard ceiling on shipped JavaScript per route, enforced rather than aspired to, with the bundle analysis that shows where it went.
- Third-party script governance
- Tag audit, load strategy and a policy for what may be added later — the single most common cause of a fast site becoming slow.
- Real-user monitoring
- Field measurement by template and device class, so regressions are found by instrumentation rather than by a client noticing.
- CI performance gates
- Lighthouse CI and bundle-size checks in the pipeline. A pull request that breaks the budget fails, the same way a broken test fails.
How a performance engagement runs
- 01
Measure the field, not the lab
Real-user data by template and device. Lab scores are a debugging tool, never the target.
- 02
Fix causes, not symptoms
Ranked by impact on the metric that is actually failing, with the effort against each so you can choose.
- 03
Set the budget
Explicit numbers for LCP, INP, CLS and shipped JavaScript, agreed with you and written down.
- 04
Gate it
The budget enters CI. From that point performance stops being a project and becomes a property of the codebase.
Our method, published
The budget we enforce
These are the numbers a release has to meet on a mid-range mobile device on a 4G connection. They are not aspirations printed in a proposal — they are gates in the pipeline, and a build that misses them does not ship.
- LCP under 2.5s (field, 75th percentile)
- INP under 200ms (field, 75th percentile)
- CLS under 0.1 (field, 75th percentile)
- JavaScript under 170KB compressed per route
- Lighthouse performance 95+ on key templates
- No render-blocking third-party script above the fold
StackCore Web Vitals·Lighthouse CI·Cloudflare·Next.js·RUM·CDN
Performance, answered directly
Lighthouse is a lab simulation on a synthetic device. Google ranks on field data from your actual visitors, whose phones and networks are usually slower. A 95 lab score alongside failing field vitals is common, and the field number is the one that counts.
Where this leads next
Technical & Editorial SEO
Foundations, architecture and content that compound — audited monthly rather than asserted annually.
Ecommerce Development
Shopify, WooCommerce and custom commerce, with the pricing rules, subscriptions and integrations your operation actually runs on.
Cloud & DevOps
Edge delivery, CDN configuration and cost tuning sit with our cloud practice.
Every capability in this practice: Web & Digital Growth
Request a performance audit
Describe what you have and what it needs to do. We will tell you what it takes.