Xdebug instruments every function call, so it sees everything and multiplies the runtime by three to five. A sampling profiler interrupts periodically and records the stack, so it…
A stylesheet in the head blocks rendering until it has loaded, and a script without defer blocks parsing until it has executed. Both are correct behaviour and both…
A touchstart or wheel listener can call preventDefault(), so the browser cannot begin scrolling until the handler has run. Every such listener therefore delays scrolling, whether or not…
The shared-folder problem that nearly killed this last year is gone. What changes in the compose file, what the new file sharing costs, and where Linux and Mac…
5.6 made many ALTER operations online, and the ones that are not — changing a column type, adding a full-text index — still copy the table while holding…
All three are resource hints and they answer different questions: what this page needs now, what the next page will need, and which server to warm up. preload…
Animating top or left makes the browser recompute layout on every frame, then repaint, then composite. Animating transform skips the first two — the element is already painted…