Performance Troubleshooting

Symptoms and checks

Slower-than-expected read

• Confirm you are importing WolfXL (from wolfxl import load_workbook).
• Ensure local build is release-optimized when benchmarking native code.
• Re-run benchmark after warm-up to avoid one-time startup effects.

Slower-than-expected modify/save

• Confirm modify=True is used when editing existing files.
• Check whether many style updates are being applied per cell.
• Compare with same workbook and same changed-cell count.

Inconsistent results

• Pin Python and dependency versions.
• Run on idle machine and avoid thermal throttling.
• Report medians, not single-run numbers.

Integrity first

Never optimize by skipping correctness checks. Pair every performance run with spot validation in Excel and automated tests.