[Perf] Windows/x86: 6 Regressions on 7/2/2026 11:21:29 PM +00:00

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#75,718 opened on Jul 7, 2026 1 comment 0 reactions 0 assignees View on GitHub

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

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Forks: 8
PR merge metrics: PR metrics pending

Description

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [901aeddd1c55f5fc5a1c1450f234dd954c430ea5](https://github.com/dotnet/runtime/commit/901aeddd1c55f5fc5a1c1450f234dd954c430ea5)
Compare | [e1979b72ccb5f916649f1d9949ef663254790c25](https://github.com/dotnet/runtime/commit/e1979b72ccb5f916649f1d9949ef663254790c25)
Diff | [Diff](https://github.com/dotnet/runtime/compare/901aeddd1c55f5fc5a1c1450f234dd954c430ea5...e1979b72ccb5f916649f1d9949ef663254790c25)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Text.Perf_Ascii

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

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

| 12.53 ns | 14.44 ns | 1.15 | 0.34 | False | | |
|

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

| 12.55 ns | 14.24 ns | 1.13 | 0.37 | False | | |

![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.Text.Perf_Ascii*'
```

### System.Text.Perf_Ascii.ToUpper_Chars(Size: 128)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Text.Perf_Ascii.ToLower_Chars(Size: 128)

#### 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.Buffers.Tests.RentReturnArrayPoolTests<Object>

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

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

| 2.54 μs | 6.41 μs | 2.53 | 0.69 | 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>.ProducerConsumer(RentalSize: 4096, ManipulateArray: False, Async: True, UseSharedPool: False)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

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

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

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

| 10.00 μs | 13.85 μs | 1.39 | 0.20 | 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.ContainsFalse*'
```

### System.Collections.ContainsFalse<Int32>.Array(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

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

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]()

| 35.56 μs | 45.98 μs | 1.29 | 0.47 | 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.SocketsHttpHandlerPerfTest*'
```

### System.Net.Http.Tests.SocketsHttpHandlerPerfTest.Get(ssl: False, chunkedResponse: True, responseLength: 1)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in BenchmarksGame.BinaryTrees_2

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

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

| 70.02 ms | 109.53 ms | 1.56 | 0.25 | 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 'BenchmarksGame.BinaryTrees_2*'
```

### BenchmarksGame.BinaryTrees_2.RunBench

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

Contributor guide

No contributing guide indexed for this repository

Research direction

Start by running the listed benchmarks from dotnet/performance with the provided filters, then inspect Perf.Ascii.cs, ArrayPoolTests.cs, and ContainsFalse.cs at the linked source ranges. Compare the reported baseline and test results on Windows/x86 and use the linked reports to investigate whether the regressions reproduce. Done means the regressions are explained and the relevant performance issue is resolved or documented.

Written by the indexing model from the issue text.

Assessment

Domain: performance, testing
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 7/2/2026 11:21:29 PM +00:00

Description

Contributor guide

Research direction

Assessment

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