⚡ Bolt: Optimize Histogram rendering - #4468
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💡 What: Replaced inline `Array.from` with an IIFE pre-allocating an array and populating it via a standard `for` loop in `Histogram.tsx`.
🎯 Why: `Array.from` uses slower iteration protocols and creates intermediate `{ length: X }` objects, which creates garbage collection pressure in high-frequency React render loops.
📊 Impact: Reduces GC overhead and iteration time during chart rendering.
🔬 Measurement: Verify rendering performance in the Chrome DevTools Performance tab when displaying high bin-count histograms.
Co-authored-by: dieterolson <198168927+dieterolson@users.noreply.github.com>
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| **Learning:** In high-frequency React render loops (e.g., generating SVG chart elements in Histogram.tsx), using inline array initialization like `Array.from({ length: X }, ...)` incurs significant overhead from iterability checks, iterator creation, and closure execution per element. This creates unnecessary garbage collection pressure and main thread stalls. | ||
| **Action:** Instead, pre-allocate arrays using an Immediately Invoked Function Expression (IIFE) with `new Array(X)` and populate them with a standard `for` loop to bypass `Array.from`'s iterator overhead. |
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When future Bolt tasks follow this new playbook, it incorrectly tells them that Array.from({ length: X }, ...) creates an iterator and that the IIFE bypasses iterator overhead. A plain { length: X } object is not iterable, so Array.from uses its array-like length/index path; the rewrite can avoid mapper invocations, but iterator creation is not the reason. Correct the rationale so this durable guidance does not encourage unnecessary IIFEs based on a nonexistent cost.
AGENTS.md reference: AGENTS.md:L193-L195
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⚡ Bolt: Optimize Histogram rendering
💡 What: Replaced inline
Array.fromwith an IIFE pre-allocating an array and populating it via a standardforloop inHistogram.tsx.🎯 Why:
Array.fromuses slower iteration protocols and creates intermediate{ length: X }objects, which creates garbage collection pressure in high-frequency React render loops.📊 Impact: Reduces GC overhead and iteration time during chart rendering.
🔬 Measurement: Verify rendering performance in the Chrome DevTools Performance tab when displaying high bin-count histograms.
PR created automatically by Jules for task 3784322776110951944 started by @dieterolson