[Perf] Windows/x86: 6 Regressions on 7/13/2026 8:32:42 PM +00:00

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#76,529 opened on Jul 21, 2026 1 comment 0 reactions 0 assignees View on GitHub

arch-x86 bdn-update branch-refs/heads/main compilationmode-tiered kind-micro Look Again os-windows perf-regression runkind-micro runtime-coreclr untriaged

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Stars: 10
Forks: 8
PR merge metrics: PR metrics pending

Description

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [a90733cc40d6c7037a37d9c2b5c2403b8cac490f](https://github.com/dotnet/runtime/commit/a90733cc40d6c7037a37d9c2b5c2403b8cac490f)
Compare | [f2b30309fd488f1c3fd41c18723a7c80a81f4c67](https://github.com/dotnet/runtime/commit/f2b30309fd488f1c3fd41c18723a7c80a81f4c67)
Diff | [Diff](https://github.com/dotnet/runtime/compare/a90733cc40d6c7037a37d9c2b5c2403b8cac490f...f2b30309fd488f1c3fd41c18723a7c80a81f4c67)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Tests.Perf_Int128

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

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

| 7.06 ns | 8.97 ns | 1.27 | 0.00 | 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.Tests.Perf_Int128*'
```

### System.Tests.Perf_Int128.CopySign(value: 1, sign: -1)

#### 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

### Regressions in System.IO.Pipes.Tests.Perf_NamedPipeStream

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

[ReadWriteAsync - Duration of single invocation]()
[ADX - Test Multi Config Graph]()

| 115.35 μs | 346.16 μs | 3.00 | 0.53 | 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.IO.Pipes.Tests.Perf_NamedPipeStream*'
```

### System.IO.Pipes.Tests.Perf_NamedPipeStream.ReadWriteAsync(size: 1000000, Options: None)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [a90733cc40d6c7037a37d9c2b5c2403b8cac490f](https://github.com/dotnet/runtime/commit/a90733cc40d6c7037a37d9c2b5c2403b8cac490f)
Compare | [1baa904ac12c971494469fc724fb3b9f7126716d](https://github.com/dotnet/runtime/commit/1baa904ac12c971494469fc724fb3b9f7126716d)
Diff | [Diff](https://github.com/dotnet/runtime/compare/a90733cc40d6c7037a37d9c2b5c2403b8cac490f...1baa904ac12c971494469fc724fb3b9f7126716d)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Net.Http.Tests.WinHttpHandlerPerfTest

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

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

| 577.90 μs | 692.95 μs | 1.20 | 0.35 | 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.Net.Http.Tests.WinHttpHandlerPerfTest*'
```

### System.Net.Http.Tests.WinHttpHandlerPerfTest.Get(ssl: True, chunkedResponse: False, responseLength: 100000)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Buffers.Tests.RentReturnArrayPoolTests<Object>

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

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

| 13.83 μs | 14.89 μs | 1.08 | 0.07 | 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.Buffers.Tests.RentReturnArrayPoolTests*'
```

### System.Buffers.Tests.RentReturnArrayPoolTests<Object>.MultipleSerial(RentalSize: 4096, ManipulateArray: True, Async: True, UseSharedPool: False)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.IO.Pipes.Tests.Perf_AnonymousPipeStream

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

[ReadWriteAsync - Duration of single invocation]()
[ADX - Test Multi Config Graph]()

| 116.60 μs | 243.83 μs | 2.09 | 0.51 | 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.IO.Pipes.Tests.Perf_AnonymousPipeStream*'
```

### System.IO.Pipes.Tests.Perf_AnonymousPipeStream.ReadWriteAsync(size: 1000000)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Reflection.Metadata.Perf_TypeName

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

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

| 737.10 ns | 795.56 ns | 1.08 | 0.13 | 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.Reflection.Metadata.Perf_TypeName*'
```

### System.Reflection.Metadata.Perf_TypeName.ParseAndGetAssemblyQualifiedName(input: typeof(System.Int32[*]))

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

Contributor guide

No contributing guide indexed for this repository

Research direction

Start with the linked regression reports and the benchmark workflow, then reproduce the listed filters on x86 Windows. Inspect the named benchmark sources, including Perf.Int128.cs, Perf.WinHttpHandler.cs, and ArrayPoolTests.cs, and compare the baseline and regression commits. Done means identifying the cause of the reported regressions and confirming the performance result after a corrective change.

Written by the indexing model from the issue text.

Assessment

Tech stack: csharp, python
Domain: operating-systems, performance, testing-qa
Issue type: Bug
Difficulty: 4/5
Estimated time: 3-5 days
Activity status: Quiet
Clarity: Needs clarification
Newbie friendliness: 35/100

[Perf] Windows/x86: 6 Regressions on 7/13/2026 8:32:42 PM +00:00

Description

Contributor guide

Research direction

Assessment

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