[Perf] Windows/x86: 1 Regression on 6/28/2026 9:49:46 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [33db1610a13c814c71deb0865a23927305eecb5a](https://github.com/dotnet/runtime/commit/33db1610a13c814c71deb0865a23927305eecb5a)
Compare | [0d3df07c6048d8cbe4f544227462cae62040e587](https://github.com/dotnet/runtime/commit/0d3df07c6048d8cbe4f544227462cae62040e587)
Diff | [Diff](https://github.com/dotnet/runtime/compare/33db1610a13c814c71deb0865a23927305eecb5a...0d3df07c6048d8cbe4f544227462cae62040e587)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Collections.IndexerSet<Int32>

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

• [ConcurrentDictionary - 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.Collections.IndexerSet*'
```

### System.Collections.IndexerSet<Int32>.ConcurrentDictionary(Size: 512)

#### 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.Collections/Indexer/IndexerSet.cs at lines 140-148 and run the provided benchmarks_ci.py command for the System.Collections.IndexerSet filter. Compare the baseline and test commits and inspect the linked test report and history graph. Done means the regression is reproduced and its cause or resolution is documented.

Written by the indexing model from the issue text.