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Performance Optimization

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Optimise Tool Usage

• Batch writes – Use a single write_values call for multi-row updates instead of multiple small calls. Each call incurs Excel interop overhead.
• Limit formatting changes – Apply formatting once on the final range rather than per column to reduce COM traffic.
• Reuse context – When running consecutive operations, keep the same workbook selection so Claude doesn’t need to re-read large ranges.

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Manage Conversation Size

• Encourage concise prompts and responses. Excessive narration increases token usage, slowing Claude’s replies.
• When you’re done with a topic, restart the conversation. This trims the history and avoids triggering compacting unnecessarily.
• If Claude starts summarising repeatedly, ask it to reset the plan or provide only the final results.

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Attachment Guidelines

• Compress PDFs or limit them to relevant pages before attaching. Oversized documents increase WebSocket payloads and model processing time.
• Use images only when necessary; textual data is cheaper to process and faster to reason about.

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Excel-Specific Tips

• Close other heavy add-ins to free up Excel’s single-threaded automation pipeline.
• Avoid running X21 while long-running formulas, recalculations, or external data refreshes are in flight.
• Keep workbook size reasonable. If datasets exceed a few hundred thousand cells, offload intermediate steps to Power Query or a database.

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Backend Monitoring

• Check %LOCALAPPDATA%\X21\X21-deno\Logs for slow tool execution metrics. Langfuse spans also display durations per tool.
• If the backend becomes unresponsive, restart the add-in (close Excel). The Deno server shuts down automatically when the process exits.
• Monitor network security tools that might inspect localhost traffic; excessive scanning can degrade WebSocket performance.