My web-based date-booking tool currently needs about 0.3 s to click a newly available date, and that lag is costing me reservations. Every performance trace I run points to the front-end, not the database or server. The moment the calendar grid appears, the “select date” routine bogs down—JavaScript churns through DOM nodes before the click actually fires. Here’s what I need: • Refactor or rewrite the selection routine so it reliably identifies and clicks the first free date in under 0.1 s under real-world load. • Keep the existing UI intact; only the underlying script should change. • Show me comparative metrics (before/after timing or a small Lighthouse/DevTools recording) to confirm the gain. The codebase is plain JavaScript with a sprinkling of jQuery; no frameworks in the critical path. If you prefer vanilla JS, event delegation, or MutationObserver tricks, I’m fine with that as long as the end result is faster and stable across Chrome, Firefox, and Edge. Hand me back the optimised script (or patch), any helper functions you added, and short notes explaining how to maintain or extend the solution.