[Perf] Windows/x64: 8 Regressions on 4/27/2026 2:35:20 PM +00:00

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#72,462 opened on May 5, 2026 1 comment 0 reactions 0 assignees View on GitHub

arch-x64 branch-refs/heads/main compilationmode-tiered kind-micro Look Again os-windows perf-regression runkind-micro runtime-coreclr

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Description

### Run Information

Name | Value
-- | --
Architecture | x64
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [0bda60e7e77cc8727586674deee087cf4b3df766](https://github.com/dotnet/runtime/commit/0bda60e7e77cc8727586674deee087cf4b3df766)
Compare | [6130a50fcc846296d5c722b8e78c3bd292519eaa](https://github.com/dotnet/runtime/commit/6130a50fcc846296d5c722b8e78c3bd292519eaa)
Diff | [Diff](https://github.com/dotnet/runtime/compare/0bda60e7e77cc8727586674deee087cf4b3df766...6130a50fcc846296d5c722b8e78c3bd292519eaa)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.IO.Tests.StreamReaderReadLineTests

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

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

| 104.88 μs | 123.56 μs | 1.18 | 0.30 | False | | |
|

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

| 30.49 μs | 34.30 μs | 1.13 | 0.14 | 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.IO.Tests.StreamReaderReadLineTests*'
```

### System.IO.Tests.StreamReaderReadLineTests.ReadLineAsync(LineLengthRange: [ 1, 8])

#### ETL Files

#### Histogram

#### JIT Disasms

### System.IO.Tests.StreamReaderReadLineTests.ReadLineAsync(LineLengthRange: [ 9, 32])

#### 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.Tests.Perf_Int128

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

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

| 45.79 ns | 63.31 ns | 1.38 | 0.01 | False | | |
|

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

| 51.90 ns | 68.80 ns | 1.33 | 0.01 | 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.Tests.Perf_Int128*'
```

### System.Tests.Perf_Int128.ToString(value: 170141183460469231731687303715884105727)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_Int128.ToString(value: -170141183460469231731687303715884105728)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in Span.Sorting

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

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

| 82.69 μs | 103.30 μs | 1.25 | 0.59 | 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 'Span.Sorting*'
```

### Span.Sorting.BubbleSortArray(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Buffers.Tests.ReadOnlySequenceTests<Byte>

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

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

| 13.82 ns | 14.96 ns | 1.08 | 0.03 | 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.ReadOnlySequenceTests*'
```

### System.Buffers.Tests.ReadOnlySequenceTests<Byte>.IterateGetPositionSingleSegment

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Text.Json.Tests.Perf_Basic

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

[WriteBasicUtf8 - Duration of single invocation]()
📝 - [Benchmark Source]()
[ADX - Test Multi Config Graph]()

| 1.18 ms | 1.32 ms | 1.12 | 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.Text.Json.Tests.Perf_Basic*'
```

### System.Text.Json.Tests.Perf_Basic.WriteBasicUtf8(Formatted: False, SkipValidation: True, DataSize: 100000)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Buffers.Tests.ReadOnlySequenceTests<Char>

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

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

| 13.82 ns | 14.93 ns | 1.08 | 0.04 | 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.ReadOnlySequenceTests*'
```

### System.Buffers.Tests.ReadOnlySequenceTests<Char>.IterateGetPositionSingleSegment

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

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[Perf] Windows/x64: 8 Regressions on 4/27/2026 2:35:20 PM +00:00

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