[Perf] Windows/x64: 5 Improvements on 8/10/2026 5:38:55 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [ab094c18ba7f4a96d145afd8b34f965c5c3ef31d](https://github.com/dotnet/runtime/commit/ab094c18ba7f4a96d145afd8b34f965c5c3ef31d)
Compare | [c12540eb53044276c55a86c3a834c662eff2872f](https://github.com/dotnet/runtime/commit/c12540eb53044276c55a86c3a834c662eff2872f)
Diff | [Diff](https://github.com/dotnet/runtime/compare/ab094c18ba7f4a96d145afd8b34f965c5c3ef31d...c12540eb53044276c55a86c3a834c662eff2872f)
Configs | CompilationMode:tiered, RunKind:micro

### Improvements in System.Formats.Tar.Tests.Perf_TarWriter

Benchmark | Baseline | Test | Test/Base | Test Quality | Edge Detector | Baseline IR | Compare IR | IR Ratio
-- | -- | -- | -- | -- | -- | -- | -- | --
|

• [GnuTarEntry_WriteEntry - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 272.65 ns | 223.93 ns | 0.82 | 0.05 | False | | |
|

• [V7TarEntry_WriteEntry - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 258.26 ns | 213.07 ns | 0.83 | 0.06 | False | | |
|

• [UstarTarEntry_WriteEntry - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 257.69 ns | 218.93 ns | 0.85 | 0.14 | False | | |
|

• [PaxTarEntry_WriteEntry - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 1.62 μs | 1.40 μs | 0.86 | 0.02 | False | | |
|

• [PaxTarEntry_WriteEntry_Async - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 1.68 μs | 1.54 μs | 0.92 | 0.01 | False | | |

![graph]()
![graph]()
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[Test Report]()

### Repro
General Docs link: https://github.com/dotnet/performance/blob/main/docs/benchmarking-workflow-dotnet-runtime.md

```cmd
git clone https://github.com/dotnet/performance.git
py .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Formats.Tar.Tests.Perf_TarWriter*'
```

### System.Formats.Tar.Tests.Perf_TarWriter.GnuTarEntry_WriteEntry

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Formats.Tar.Tests.Perf_TarWriter.V7TarEntry_WriteEntry

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Formats.Tar.Tests.Perf_TarWriter.UstarTarEntry_WriteEntry

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Formats.Tar.Tests.Perf_TarWriter.PaxTarEntry_WriteEntry

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Formats.Tar.Tests.Perf_TarWriter.PaxTarEntry_WriteEntry_Async

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

[Profiling workflow for dotnet/runtime repository](https://github.com/dotnet/performance/blob/master/docs/profiling-workflow-dotnet-runtime.md)
[Benchmarking workflow for dotnet/runtime repository](https://github.com/dotnet/performance/blob/master/docs/benchmarking-workflow-dotnet-runtime.md)

Start with the benchmark source in performance/src/benchmarks/micro/libraries/System.Formats.Tar/Perf.Tar.cs at the listed lines, then run the provided benchmarks_ci.py command for Perf_TarWriter. The report identifies timing improvements across five benchmarks, but gives no target code change or acceptance criterion, so completion cannot be determined from this issue alone.

Written by the indexing model from the issue text.