Field data before lab data
A synthetic score describes one run on one machine. Real user measurements describe what your customers get on the devices and networks they actually have, which is what Google uses and what the business feels.
Optimisation
Everyone Measures.Almost NobodyFixes The Cause.
A performance report is not performance work. The score tells you the page is slow. Finding out why usually means reproducing the conditions that cause it, which is rarely what happens on a developer laptop with a fast connection.
What is performance engineering at The Cubas?
The Cubas diagnoses and fixes slow web applications across Core Web Vitals, JavaScript bundle size, image delivery, caching strategy and database query performance. Work is measured before and after with both lab and field data, so the improvement is demonstrated rather than claimed.
When people call us
The Moment This Becomes Urgent
Failing Core Web Vitals in Search Console, a mobile experience that loses people before it renders, or a database that was fine until the table reached a few million rows.
Built by
Ashraful Islam Hridoy, Lead Engineer
Ashraful builds the systems behind The Cubas engineering work, from typed REST APIs and data models to the React interfaces on top of them. His focus is the part most builds skip: secure access, reliable background jobs, and what happens to a system after launch.
What people search before they call
- Core Web Vitals fix agency
- website speed optimisation UK
- reduce JavaScript bundle size
- improve Largest Contentful Paint
- slow database query optimisation
We rank for these ourselves. That is the shortest demonstration available that the search side and the build side are the same team.
How we approach it
What Actually Decides A Performance Project
Four decisions that separate a build which holds up from one that needs rescuing inside a year.
Ship less JavaScript
Bundle analysis, code splitting and moving work to the server. On this site the same audit removed an animation library that cost forty four kilobytes on every page to do what CSS transitions already did.
Fix the query, not the cache
Caching a slow query hides it until the cache misses. Indexing strategy and query shape come first, as with the MongoDB indexing work that cut response times on production systems.
Reproduce load before diagnosing it
Some faults only appear under concurrency. The SwiftCart connection leak was invisible in development and only showed when Atlas warned production was near its limit. Finding that meant recreating the load, not rereading the code.
Deliverables
What You Actually Receive
No tiered packages with features withheld to force an upgrade. Every engagement covers what the project genuinely requires.
Stack for this work
- Lighthouse
- Chrome DevTools
- Next.js
- Vercel Analytics
- PostgreSQL
- MongoDB
Core Web Vitals audit using field and lab data
JavaScript bundle reduction and code splitting
Image, font and asset delivery pipeline
Caching and revalidation strategy
Database index and query tuning
Evidence
Builds That Prove This
Not a capability list. Systems in production, described by what was genuinely hard about each one.
ProductionEcommerce · 2025
SwiftCart
Home and decor store, hardened after launch
A home and decor storefront with customer and admin dashboards, Chart.js reporting and PDF invoices, maintained in production across more than 200 commits.
- Next.js
- Tailwind CSS
- TanStack Query
- MongoDB
- Mongoose
- +2
LiveBooking · 2024
Stay Booking
Hotel booking from search to payment
A booking application covering listing discovery, reservations, property management and payment, with seeded demo accounts so anyone can walk the full flow.
- Next.js
- Tailwind CSS
- MongoDB
- Mongoose
- NextAuth
- +1
Questions
What Clients Ask First
Do Core Web Vitals actually affect rankings?
They are a confirmed ranking signal, though a modest one next to relevance and authority. The larger effect is commercial: slow pages lose people before they read anything, so the conversion impact usually exceeds the ranking impact.
What targets do you work to?
Largest Contentful Paint under 2.5 seconds, Cumulative Layout Shift under 0.1 and Interaction to Next Paint under 200 milliseconds on mobile, measured on real users. We build to tighter internal budgets so there is room before the threshold.
Can you speed up a WordPress site without rebuilding it?
Often, to a point. Caching, image handling and removing plugin bloat produce real gains. When page builder markup makes the targets unreachable no amount of tuning will fix it, and we will tell you when you have hit that ceiling rather than billing for diminishing returns.
Other engineering services
Tell Us What You Need Built
Send the brief, the existing codebase or just the problem. We will tell you what it takes, what it does not need, and whether we are the right people for it.
Prefer to skip the form? Message us on WhatsApp or email yousuf@thecubas.com