[Perf] Windows/x86: 1 Improvement on 4/9/2026 7:19:09 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [ab2f538fca8e2d278e592da1dd6e6ad82954e91c](https://github.com/dotnet/runtime/commit/ab2f538fca8e2d278e592da1dd6e6ad82954e91c)
Compare | [cc78323ef440208bab9bd99fee82e3ea40ec61a5](https://github.com/dotnet/runtime/commit/cc78323ef440208bab9bd99fee82e3ea40ec61a5)
Diff | [Diff](https://github.com/dotnet/runtime/compare/ab2f538fca8e2d278e592da1dd6e6ad82954e91c...cc78323ef440208bab9bd99fee82e3ea40ec61a5)
Configs | CompilationMode:tiered, RunKind:micro

### Improvements in System.IO.Tests.Perf_FileStream

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

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

[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.IO.Tests.Perf_FileStream*'
```

### System.IO.Tests.Perf_FileStream.WriteAsync_NoBuffering(fileSize: 1048576, userBufferSize: 16384, options: Asynchronous)

#### 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 at performance/src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.FileStream.cs:314-318 and the linked WriteAsync_NoBuffering report. Follow the benchmarking workflow and run the provided benchmarks_ci.py command to validate the Windows/x86 result, then inspect relevant runtime changes. Done means the improvement is explained and any needed follow-up is recorded.

Written by the indexing model from the issue text.