Website + bookings / Tourism
A site with real-time availability, online payment and routes across Andalusia in nine languages, optimised after a mobile performance audit that found where the seconds were being lost.
Project sheet
sundaycampers.es
A campervan hire business sells mainly to foreign tourists comparing options on their phones, sometimes from abroad and in a hurry. It needs to show real availability, take payment without intermediaries and appear in several languages. The mobile audit in August 2026 showed that the main image took almost five seconds to render, not because of its size but because of avoidable waits.
02 / Context
The audit broke the problem into measurable parts. 65% of the delay was time spent waiting for the main image to start loading, because the element did not exist until the page hydrated. On top of that came two analytics containers running in parallel, a redirect from the root to the Spanish version costing around 700 ms and images linked from third-party domains.
03 / Solution
The website is built with Next.js on Supabase and Stripe. Availability is read from a daily view per vehicle and synced with external calendars via iCal. The price is recalculated on the server before the payment is created, and the database itself prevents two bookings from overlapping. After the audit, each cause it found was fixed in the code, one by one.
Exclusion constraint in Postgres so two bookings cannot overlap
Price recalculated on the server, without trusting the total sent by the browser
Checkout with an idempotency key and a webhook with a verified signature
Hero rendered on the server with high priority instead of waiting for hydration
Per-language hreflang with x-default and a sitemap with real modification dates
Overbooking is prevented in the database, not in the interface. Even if two payments arrive at once, Postgres rejects the second.
Each fix responds to a measured audit finding, not to a generic list of best practices.
Visitors arrive in many languages, so routes, vehicles and landing pages each have their own version with reciprocal hreflang.
04 / Scope
05 / Results
The main image is now rendered on the server with high priority, a single analytics container remains and loads deferred, the root resolves with a rewrite instead of a redirect and all images are served from the site's own domain. The site still needs to be re-measured with the same method before the after figures are published; once they are, they will appear here with their date.
06 / Questions
Because we only publish numbers measured with a stated method and date. The fixes are in the code; the new PageSpeed Insights measurement, using the median of several runs, will be published on this page once it is done.
Downloading the image took about 126 ms. The time went on waiting: almost 1.8 seconds before it started loading, because the element was not in the initial HTML, and another 0.8 seconds before it could be painted.