A fair question deserves a fair answer: the people who build Wix and Squarespace are good engineers. The sites still feel heavy, and the reason is structural, not sloppy.
A builder page is assembled from generic blocks, and every block has to work for every business at once. The booking widget has to handle salons and scaffolders. The gallery has to survive being fed forty full-resolution photos by someone who has never heard of image compression, because nobody should have to hear about image compression. All that defensive machinery ships to your visitor whether your site uses it or not.
The weight you cannot see
- Scripts for features your site does not use, loaded because the platform cannot know you will never use them.
- Styling for every theme variant, carried by all of them.
- Third-party plugins, each with its own baggage and its own update schedule.
- Tracking, telemetry, and upsell machinery that serves the platform rather than you.
None of it is visible on a designer's fast laptop with fibre broadband. It is very visible on a five-year-old phone on one bar of signal in a car park, which is where your actual customer is trying to find your phone number.
The alternative is subtraction
A built site inverts the equation. It carries exactly what it needs, because someone decided what it needs. Our builds ship no third-party plugins, no speculative machinery, and no tracking that serves anyone but you. That is most of the secret. Speed is rarely something you add to a website; it is what remains when you stop adding everything else.