[Perf] Windows/x64: 1 Regression on 9/2/2026 5:37:42 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [f00a5ba2dde9f648bcd9ac77411d1a8596449303](https://github.com/dotnet/runtime/commit/f00a5ba2dde9f648bcd9ac77411d1a8596449303)
Compare | [696fda84063459254633ad07bf8ce1e6977c9ad5](https://github.com/dotnet/runtime/commit/696fda84063459254633ad07bf8ce1e6977c9ad5)
Diff | [Diff](https://github.com/dotnet/runtime/compare/f00a5ba2dde9f648bcd9ac77411d1a8596449303...696fda84063459254633ad07bf8ce1e6977c9ad5)
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_NonFlags_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_NonFlags_Large(value: Format)

#### 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 src/benchmarks/micro/libraries/System.Runtime/Perf.Enum.cs at lines 48-55 and run the provided benchmarks_ci.py command with the System.Tests.Perf_Enum filter. Compare the baseline and test commits, then review the linked test report, history graph, and IR data to identify the cause of the ToString_NonFlags_Large slowdown. Done means the regression is explained and addressed or correctly triaged.

Written by the indexing model from the issue text.