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Performance Triage Runbook for Legacy .NET

Step-by-step runbook to find the top 3 bottlenecks in legacy .NET applications—prioritized by quick-win vs. structural effort.

FreeFeb 26, 2026

What’s inside

Individual files are accessible (best for SEO/AI), plus you can download the full ZIP.

bottleneck-classification-checklist.mdmddotnet-counters-cheatsheet.mdmdperformance-triage-runbook.mdmdREADME.mdmd

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Performance triage in legacy .NET: find the top 3 bottlenecks fast
When the legacy system is slow and no one knows where to start, a structured triage finds the real bottlenecks in hours, not weeks. This playbook gives you a repeatable method to identify, rank, and fix the top 3 performance killers.
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What's Inside

A systematic method to identify performance bottlenecks in legacy .NET applications without requiring deep codebase knowledge or complex tooling.

Files in This Package

FilePurpose
performance-triage-runbook.mdStep-by-step 4-phase triage method from symptom to fix
dotnet-counters-cheatsheet.mdQuick reference for metrics, thresholds, and commands
bottleneck-classification-checklist.mdDecision framework for quick-win vs. structural fixes

Perfect For

  • Taking over legacy applications with unknown performance characteristics
  • Emergency triage when latency spikes hit production
  • Building baseline performance profiles for inherited systems
  • Teams without dedicated performance engineering resources

The 4-Phase Method

  1. Classify the symptom — CPU-bound? Memory-bound? I/O-bound?
  2. Collect baseline metrics — Using dotnet-counters (5-minute capture)
  3. Identify top 3 culprits — Ranked by impact
  4. Apply fixes in priority order — Quick wins first, structural changes later

No trial-and-error. No guessing. No sifting through years of commits.

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