[Perf] Windows/x86: 1 Regression on 8/13/2026 11:48:29 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [2580b590a05d8094853482acf0faa9ecbf06f2fc](https://github.com/dotnet/runtime/commit/2580b590a05d8094853482acf0faa9ecbf06f2fc)
Compare | [afb1dc1f8fbffeb5afda4ec624695ae8ddd2960d](https://github.com/dotnet/runtime/commit/afb1dc1f8fbffeb5afda4ec624695ae8ddd2960d)
Diff | [Diff](https://github.com/dotnet/runtime/compare/2580b590a05d8094853482acf0faa9ecbf06f2fc...afb1dc1f8fbffeb5afda4ec624695ae8ddd2960d)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Tests.Perf_Enum

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

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

![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.Tests.Perf_Enum*'
```

### System.Tests.Perf_Enum.ToString_Format_Flags_Large(value: All, format: "x")

#### 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 System.Tests.Perf_Enum benchmark source at performance/src/benchmarks/micro/libraries/System.Runtime/Perf.Enum.cs#L70-L77 and run the provided benchmarks_ci.py command. Compare the baseline and test commits, then inspect the linked history, graph, and test report for ToString_Format_Flags_Large. Done means the regression is reproduced and its cause or next investigation step is documented.

Written by the indexing model from the issue text.