First impressions matter. You only have a few milliseconds to make one on the web. How users experience the first few moments of working with your application will influence their entire experience. Looking at a white browser screen for 5 seconds is NOT a good first impression. We can do better without a lot of effort by organizing the way our assets load and are cached. Let's talk details. What kind of cache control header should you send with a fingerprinted asset? How can you add a kill switch to a service worker to avoid leaving your users with a broken application? What makes a javascript application installable as a PWA? How can you notify users that a new version of your app is available? As the Lead Developer and Architect for the Ilios Project I've answered all of these questions in production on an open source application used by health science universities on 5 continents.