When every byte matters and you need to support every user and every device, you need to embrace progressive enhancement from the service worker up. Supporting users who may not support Progressive Web Apps, on low-end devices, on expensive pre-paid internet plans, or while offline, requires rethinking of the core architecture of most PWAs. Performant progressive enhancement provides an approach that a research team at Illinois Institute of Technology in Chicago, in partnership with Howard Brown Health, has developed for these needs, allowing them, and you, to improve PWA user engagement for everyone