docs(research): pretable scroll-with-render perf diagnostic (noise verdict)#133
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Three-phase research PR mirroring PR #124's pattern: high-repeat (n=20) re-run, conditional Playwright trace capture, research memo. Diagnoses whether the PR #130 cheap-render anomaly (16.4 ms vs 10.3 ms for format and heavy-render) is real or a low-sample artifact. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Seven-task plan mirroring PR #124's three-phase pattern: n=20 matrix re-run, conditional Playwright trace capture, research memo. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Verdict: noise. The PR #130 cheap-render anomaly (16.4 ms vs ~10.3 ms for format and heavy-render at n=3) was a sampling artifact. At higher repeats, scroll-with-render is at parity with (in fact marginally faster than) the other two: | Script | n | mean (ms) | σ (ms) | | -------------------------- | --: | --------: | -------: | | scroll-with-format | 8 | 9.36 | 0.80 | | scroll-with-render | 7 | 8.97 | 0.35 | | scroll-with-heavy-render | 6 | 9.15 | 0.13 | Both 2σ pairs (cheap-vs-format, cheap-vs-heavy) are well within the noise floor. Same shape as PR #124's finding at larger magnitude. The matrix run completed only ~36% of planned repeats (Playwright flake; not investigated) but the observed σ values make the verdict unambiguous — PR #130's 6 ms gap is ~21σ away from the observed distribution. No perf-fix PR needed. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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…get on pretable filter-text) (#134) * docs(specs, plans): interaction borderline perf diagnostic Tightens PR #131's two borderline numbers (pretable filter-text 17.7 ms, tanstack vs pretable filter-metadata 15.7/16.0 ms) via n=20 re-run. Mirrors PR #124 / PR #133's pattern. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com> * docs(research): interaction borderline perf diagnostic memo Verdict: pretable filter-text is real-over-budget (16.79 ± 0.31 ms at n=20); tanstack vs pretable filter-metadata is noise-tied (1.6 ms mean diff vs 23 ms 2σ noise floor — tanstack's σ at n=8 is 11.6 ms). Incidental finding: pretable filter-metadata is also over budget at the mean (17.51 ± 2.44 ms). PR #131's 16.0 ms n=3 reading was a low-end sample. Homepage prose claims filter-metadata is "clear of" the single-frame budget; that's no longer accurate. Three recommendations queued (editorial cleanup + perf-fix investigation); see memo for details. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com> * chore: prettier-format borderline diag artifacts --------- Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>
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* docs(specs): pretable wrapped-text filter perf diagnostic design Three-phase pattern (trace + analyze + memo) with conditional fix in same PR. Mirrors PR #124 / PR #133 with a Phase D escape hatch for single-cause low-risk fixes. Targets pretable's interaction scripts landing 1-2 ms over the 16 ms single-frame budget on Chromium S2/hypothesis (PR #134 finding). Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com> * docs(plans): pretable wrapped-text filter perf diagnostic plan Five-task plan: trace capture, manual analysis, memo, conditional fix, gates + PR. Auto-merge if memo-only; hold if a fix ships. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com> * chore(bench): Playwright trace for pretable filter-text perf diagnostic * docs(research): pretable wrapped-text filter perf diagnostic memo * style(docs): prettier format perf diagnostic memo + plan + spec * chore: remove force-added trace binary; project convention is no committed traces The trace was captured locally per the spec but force-added past .gitignore — the project's standing pattern is `status/traces/*.zip` is gitignored. Removing the binary; memo updated to note the trace is local-only and that Playwright's default action-trace format doesn't capture per-function timeline data anyway (the real blocker for this investigation, separately documented in the memo's "bench-harness gap" follow-up). Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com> * docs(research): memo references local-only trace; no committed binary The trace path reference in the memo was pointing at a binary that was force-added past .gitignore and then removed in the prior commit. Update the reference to note the trace is local-only and the Playwright action-trace format wouldn't have given flame-graph data anyway. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>
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Summary
Diagnoses whether pretable's `scroll-with-render` 6 ms gap from PR #130 (16.4 ms vs ~10.3 ms for format + heavy-render at n=3) is real or a low-sample artifact. Verdict: noise. Mirrors PR #124's pattern at larger magnitude.
Verdict
At higher repeats, `scroll-with-render` is at parity with (in fact marginally faster than) `scroll-with-format` and `scroll-with-heavy-render`:
Both 2σ pairs are well within the noise floor:
The PR #130 cheap-render value of 16.4 ms is ~21σ away from the observed distribution — statistically impossible at this sample size.
No perf-fix PR needed. No React-reconciliation cliff exists between single-text-child and multi-child spans in pretable's MemoizedCellContent path.
Sample size caveat
The matrix completed only ~36 % of planned repeats (Playwright flake; not investigated). Sample counts came out 6–8 per script instead of n=20. Documented in the memo; the observed σ values make the verdict unambiguous regardless — a 6 ms gap couldn't hide in this distribution.
What's NOT in this PR
Test plan
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