XLSX codec performance

Validated evidence. 5 compared operations over 5 process-isolated rounds each, from one checked corpus fixture.

Current and baseline are the same codec at different commits, measured in the same session. Baseline commit: 87fadb723979.

Operation time

operationlog scale — every tick is 10× — shorter is fastermedianp95

Export rich

Current370 ms387 ms

Baseline697 ms711 ms

Export scalar

Current442 ms458 ms

Baseline601 ms605 ms

Export shared style

Current688 ms709 ms

Baseline1.25 s1.31 s

Export sparse

Current65.3 ms67.8 ms

Baseline185 ms188 ms

Import combined

Current1.23 s1.25 s

Baseline10.1 s10.8 s

Reject compression ratio

Current2.69 ms2.99 ms

Reject deep xml

Current8.78 ms9.58 ms

Peak resident memory

operationlinear scale — shorter uses less memorymedianp95

Export richMaximum peak RSS: current 148.2 MB · baseline 182.7 MB

Current138.9 MiB141.0 MiB

Baseline171.8 MiB173.9 MiB

Export scalarMaximum peak RSS: current 167.2 MB · baseline 208.7 MB

Current157.4 MiB159.2 MiB

Baseline197.2 MiB198.7 MiB

Export shared styleMaximum peak RSS: current 174.0 MB · baseline 297.2 MB

Current164.0 MiB165.6 MiB

Baseline281.2 MiB283.1 MiB

Export sparseMaximum peak RSS: current 96.0 MB · baseline 113.0 MB

Current90.5 MiB91.5 MiB

Baseline106.9 MiB107.6 MiB

Import combinedMaximum peak RSS: current 218.0 MB · baseline 3612.9 MB

Current206.7 MiB207.8 MiB

Baseline3,402.0 MiB3,437.5 MiB

Reject compression ratioMaximum peak RSS: current 46.7 MB

Current43.9 MiB44.4 MiB

Reject deep xmlMaximum peak RSS: current 49.7 MB

Current46.7 MiB47.4 MiB

All measurements

Captured: 2026-10-29 03:40 UTC
Commit: ac4ab632d80a clean worktree
Engines: Sheetwrite 0.5.4 · ExcelJS 4.4.0 at baseline 87fadb723979
Fixture: bench/fixtures/xlsx-codec-corpus.xlsx · 1,038,346 bytes · 2633e51a4a3c · LibreOffice 26.2.4.2 Calc MS Excel 2007 XML
Environment: Bun 1.4.4 · Node v26.3.0 · 12th Gen Intel(R) Core(TM) i9-12900H
Raw artifact: bench/results/xlsx-results.json

Reproduce with a checkout of the baseline commit, built and passed as the comparison root:

git worktree add ../sheetwrite-xlsx-baseline 87fadb72397947ea8c6ba576682925c7879579b8
cd ../sheetwrite-xlsx-baseline && bun install --frozen-lockfile && bun run build:packages
cd - && bun run --filter @sheetwrite/bench bench:xlsx -- --baseline-root ../sheetwrite-xlsx-baseline

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