Agent skill · Content & Marketing

build-perf-diagnostics

Diagnose MSBuild build performance bottlenecks using binary log analysis. USE FOR: identifying why builds are slow by analyzing binlog performance summaries, detecting ResolveAssemblyReference (RAR) taking >5s, Roslyn analyzers consuming >30% of Csc time, single targets dominating >50% of build time, node utilization below 80%, excessive Copy tasks, NuGet restore running every build. Covers timeline analysis, Target/Task Performance Summary interpretation, and 7 common bottleneck categories. Use after build-perf-baseline has established measurements. DO NOT USE FOR: establishing initial baseli

dotnetgithub.com/dotnetGitHub ↗
claude-codeMIT
Install
npx skills add dotnet/skills --skill build-perf-diagnostics --agent claude-code

Same command for any agent — swap --agent for codex, cursor, copilot.

Facts
Files in the skill folder: 1
SKILL.md size: 10 KB
Bundled scripts: none
Path: plugins/dotnet-msbuild/skills/build-perf-diagnostics/SKILL.md
Open the folder on GitHub →
Where it comes from
Stars: 4,927
Language: C#
Read our review of the source →

Weekly change comes from our own snapshots, not the repository page — it measures attention, not adoption.

From the SKILL.md

## Performance Analysis Methodology 1. **Generate a binlog**: `dotnet build /bl:{} -m` 2. Use the **binlog MCP server** (`Microsoft.AITools.BinlogMcp`, exposed under the `binlog` MCP namespace) which is bundled with this plugin ### Alternate flow when MCP is unavailable: binlog replay to text logs 1. **Generate a binlog**: `dotnet build /bl:{} -m` 2. **Replay to diagnostic log with performance summary**: ```bash dotnet msbuild build.binlog -noconlog -fl -flp:v=diag;logfile=full.log;performancesummary ``` 3. **Read the performance summary** (at the end of `full.log`): ```bash grep "Target Performance Summary\|Task Performance Summary" -A 50 full.log ``` 4. **Find expensive targets and tasks**: The PerformanceSummary section lists all targets/tasks sorted by cumulative time 5. **Check for node utilization**: grep for scheduling and node messages ```bash grep -i "node.*assigned\|building with\|scheduler" full.log | head -30 ``` 6. **Check analyzers**: grep for analyzer timing ```bash grep -i "analyzer.*elapsed\|Total analyzer execution time\|CompilerAnalyzerDriver" full.log ``` ## Key Metrics and Thresholds - **Build duration**: what's "normal" — small project <10s, medium <60s, large

What's inside
Steps it walks through
  1. Performance Analysis Methodology
  2. Alternate flow when MCP is unavailable: binlog replay to text logs
  3. Key Metrics and Thresholds
  4. Common Bottlenecks
  5. 1. ResolveAssemblyReference (RAR) Slowness
  6. 2. Roslyn Analyzers and Source Generators
  7. 3. Serialization Bottlenecks (Single-threaded targets)
  8. 4. Excessive File I/O (Copy tasks)
  9. 5. Evaluation Overhead
  10. 6. NuGet Restore in Build
  11. 7. Large Project Count and Graph Shape
  12. Using Binlog Replay for Performance Analysis
  13. Quick Wins Checklist
  14. Impact Categorization
Commands it runs
dotnet msbuild build.binlog -noconlog -fl -flp:v=diag;logfile=full.log;performancesummary
grep "Target Performance Summary\|Task Performance Summary" -A 50 full.log
grep -i "node.*assigned\|building with\|scheduler" full.log | head -30
grep -i "analyzer.*elapsed\|Total analyzer execution time\|CompilerAnalyzerDriver" full.log
grep "done building project\|Project Performance Summary" full.log
grep -i "node.*assigned\|RequiresLeadingNewline\|Building with" full.log | head -30
grep -i "Total analyzer execution time\|analyzer.*elapsed\|CompilerAnalyzerDriver" full.log
grep 'Target "CoreCompile"\|Target "ResolveAssemblyReferences"' full.log
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About this skill
What does the build-perf-diagnostics skill do?

Diagnose MSBuild build performance bottlenecks using binary log analysis. USE FOR: identifying why builds are slow by analyzing binlog performance summaries, detecting ResolveAssemblyReference (RAR) taking >5s, Roslyn analyzers consuming >30% of Csc time, single targets dominating >50% of build time, node utilization below 80%, excessive Copy tasks, NuGet restore running every build. Covers timeline analysis, Target/Task Performance Summary interpretation, and 7 common bottleneck categories. Use after build-perf-baseline has established measurements. DO NOT USE FOR: establishing initial baseli

How do I install it?

Run `npx skills add dotnet/skills --skill build-perf-diagnostics --agent claude-code` — it drops the skill into your project so the agent can pick it up. Swap the --agent value for codex, cursor or copilot if you use one of those.

Where does this skill come from?

From dotnet/skills, a repository with 4,927 stars. We read it straight from the repository tree rather than a submitted listing, so what you see here is what is actually published.

Is a popular skill a good skill?

Not necessarily. Stars measure attention, not adoption — a repository can trend for a week and be abandoned. That is why we show the weekly change from our own snapshots next to the total, instead of a single flattering number.

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