Powerwincher
Shona’s company builds electric winch handles for sailboats in Kettering and sells them to cruisers and racers worldwide. The site priced only in AUD, couldn’t tell where a visitor was, and slowed down or crashed under load. It went down completely while she was at the Annapolis Boat Show, the biggest sailing show in the US.
I rebuilt it from scratch while they were still at the show: multi-currency pricing built into the store rather than bolted on, IP-based location detection to pick the right currency as the page loads, and a sturdier setup with caching that holds up when a boat show sends traffic at it. It was live before they flew home.