[Perf] Windows/x86: 4 Regressions on 8/8/2026 4:13:10 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [7da460b99b9c7e76b3060ef6da6687a008263ab9](https://github.com/dotnet/runtime/commit/7da460b99b9c7e76b3060ef6da6687a008263ab9)
Compare | [f5f5f83dd8676416636eda75d8c091c6c4f8d506](https://github.com/dotnet/runtime/commit/f5f5f83dd8676416636eda75d8c091c6c4f8d506)
Diff | [Diff](https://github.com/dotnet/runtime/compare/7da460b99b9c7e76b3060ef6da6687a008263ab9...f5f5f83dd8676416636eda75d8c091c6c4f8d506)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Collections.IterateForEach<String>

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

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

| 1.96 μs | 2.61 μs | 1.34 | 0.28 | False | | |
|

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

| 1.40 μs | 1.67 μs | 1.19 | 0.16 | False | | |
|

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

| 1.54 μs | 1.67 μs | 1.08 | 0.23 | False | | |

![graph]()
![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.IterateForEach*'
```

### System.Collections.IterateForEach<String>.LinkedList(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Collections.IterateForEach<String>.HashSet(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Collections.IterateForEach<String>.Queue(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)

---

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [7da460b99b9c7e76b3060ef6da6687a008263ab9](https://github.com/dotnet/runtime/commit/7da460b99b9c7e76b3060ef6da6687a008263ab9)
Compare | [f5f5f83dd8676416636eda75d8c091c6c4f8d506](https://github.com/dotnet/runtime/commit/f5f5f83dd8676416636eda75d8c091c6c4f8d506)
Diff | [Diff](https://github.com/dotnet/runtime/compare/7da460b99b9c7e76b3060ef6da6687a008263ab9...f5f5f83dd8676416636eda75d8c091c6c4f8d506)
Configs | CompilationMode:tiered, RunKind:micro

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

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

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

| 1.54 μs | 1.94 μs | 1.26 | 0.60 | False | | |

![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.IterateForEach*'
```

### System.Collections.IterateForEach<Int32>.LinkedList(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 by running the benchmark command in the Repro section for System.Collections.IterateForEach and IterateForEach. Read src/benchmarks/micro/libraries/System.Collections/Iterate/IterateForEach.cs at the linked benchmark lines, then compare the baseline and test commits and inspect the linked reports. Done means identifying the regression cause and confirming the affected benchmarks no longer regress on Windows/x86.

Written by the indexing model from the issue text.