Most agency sites are a theme with the colours changed. That is why they all feel the same, and why they all load slowly. You inherit every feature you are not using.
We build the front-end ourselves. That costs more up front and pays back in two places: the site looks like nothing else in your category, and it stays fast enough to rank.
Performance is a budget we agree before design starts, not something we measure afterwards and apologise for. If a scene blows the budget, the scene gets cheaper.