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// Measure jQuery operation speed console.time("selector"); const $items = $(".complex-selector > .child:not(.hidden)"); console.timeEnd("selector"); // Chrome DevTools: // 1. Performance tab → Record → interact → Stop // 2. Look for: Long Tasks (>50ms), Forced Layout/Reflow (yellow) // 3. Layers tab: check what is GPU-composited // Mark code boundaries for profiling: performance.mark("query-start"); $(".items").filter(":visible").each(fn); performance.mark("query-end"); performance.measure("query", "query-start", "query-end");
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