Most people think the difference between a custom website and a template is how it looks. It's not. A well-designed template and a well-designed custom site can look nearly identical to a visitor.
The difference is in how they're built — and that difference shows up directly in performance scores, search rankings, and whether or not the phone rings.
Templates are built to fit everyone. Which means they're optimized for no one. The code carries functionality for dozens of use cases you'll never use. The structure is generic because it has to be flexible enough to work for a photographer and a plumber and a restaurant and a law firm. That flexibility is exactly what makes it fail at any of them specifically.
A custom site is built around your business. Your services. Your locations. Your customers. That specificity is what makes it perform — for search, for conversion, and for growth over time.