A handy little for calculating your performance budget based on how long you want your page to take to load on a particular connection.
Some good practical advice from Tim on setting a performance budget.
Use rule-based metrics to make sure you haven’t overlooked simple optimizations.
Use quantity-based metrics as guides to help designers and developers make better decisions about what goes onto a page.
Superb in-depth analysis of Ryanair’s website dark patterns and nasty brand strategy.