Client: EU home-goods store, 25k orders / month.
Problem: Shared hosting timing out under peak load, checkout failures during flash sales.
Fix: Built a full staging clone on a DigitalOcean droplet, tuned Nginx + Redis + OPcache, cut over DNS with a delta order sync at the moment of switch.
Result: TTFB down from 1.8s to 210ms, checkout errors gone, zero orders lost during the move.