Why the developer machine is the wrong yardstick, which reference device matches the 75th percentile and how both turn into a performance budget that holds.
Why anti-flicker layers push out Largest Contentful Paint, how to measure their share of the first paint and which setups carry a test without hiding the page.
How load time becomes a verifiable acceptance criterion: target value, method, data source and proof date per metric – and what German contract law makes of it.
Farewell events often fail to deliver the final measurement on mobile. How fetchLater() fixes that, which quota applies and what the fallback looks like.
How much CSS a page really needs, how to measure the unused share reliably and in which order to remove ballast without breaking the rendering.
TTFB only gives you the sum. The Server-Timing header breaks server time down in the browser into database, cache, application logic and template work.
The interface starts fast and turns sluggish after twenty minutes: how front-end memory leaks arise, how to measure them over time and how to get rid of them.
A page answering in 400 ms on a single request can break at 300 concurrent visitors. How a load test makes capacity visible before the peak season starts.
Between web server and database sits the PHP runtime. How OPcache, preloading, JIT and FPM workers shape your response time under load, and how to measure it.