[Perf] Windows/x64: 15 Regressions on 8/28/2026 12:45:54 PM +00:00

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#79,052 opened on Sep 8, 2026 1 comment 0 reactions 0 assignees View on GitHub

arch-x64 branch-refs/heads/main compilationmode-tiered kind-micro 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 | x64
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [3174387aedaebdb35da41426e61ecc1b8d60bc47](https://github.com/dotnet/runtime/commit/3174387aedaebdb35da41426e61ecc1b8d60bc47)
Compare | [398b6c5d572103decd5cfec64121384bcffc01bc](https://github.com/dotnet/runtime/commit/398b6c5d572103decd5cfec64121384bcffc01bc)
Diff | [Diff](https://github.com/dotnet/runtime/compare/3174387aedaebdb35da41426e61ecc1b8d60bc47...398b6c5d572103decd5cfec64121384bcffc01bc)
Configs | CompilationMode:tiered, RunKind:micro

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

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

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

| 54.84 ns | 59.92 ns | 1.09 | 0.03 | False | | |
|

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

| 55.24 ns | 58.95 ns | 1.07 | 0.04 | False | | |
|

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

| 55.02 ns | 58.35 ns | 1.06 | 0.04 | 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.CtorGivenSize*'
```

### System.Collections.CtorGivenSize<Int32>.Queue(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Collections.CtorGivenSize<Int32>.List(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Collections.CtorGivenSize<Int32>.Stack(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

### Regressions in System.Threading.Tests.Perf_Timer

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

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

| 86.14 ns | 134.84 ns | 1.57 | 0.16 | False | | |
|

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

| 79.28 ns | 117.39 ns | 1.48 | 0.19 | False | | |
|

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

| 326.99 ms | 378.34 ms | 1.16 | 0.27 | 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.Threading.Tests.Perf_Timer*'
```

### System.Threading.Tests.Perf_Timer.ShortScheduleAndDisposeWithFiringTimers

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Threading.Tests.Perf_Timer.LongScheduleAndDispose

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Threading.Tests.Perf_Timer.ScheduleManyThenDisposeMany

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Security.Cryptography.Tests.Perf_CryptoConfig

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

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

| 222.42 ns | 281.02 ns | 1.26 | 0.17 | False | | |
|

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

| 205.10 ns | 234.38 ns | 1.14 | 0.17 | 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.Security.Cryptography.Tests.Perf_CryptoConfig*'
```

### System.Security.Cryptography.Tests.Perf_CryptoConfig.CreateFromName(name: "RSA")

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Security.Cryptography.Tests.Perf_CryptoConfig.CreateFromName(name: "X509Chain")

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Tests.Perf_GC<Byte>

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

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

| 48.99 ns | 58.06 ns | 1.19 | 0.07 | False | | |
|

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

| 26.64 ns | 29.40 ns | 1.10 | 0.03 | 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_GC*'
```

### System.Tests.Perf_GC<Byte>.AllocateArray(length: 1000, pinned: False)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_GC<Byte>.AllocateUninitializedArray(length: 1000, pinned: False)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Memory.Memory<Byte>

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

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

| 26.59 ns | 28.23 ns | 1.06 | 0.02 | 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.Memory.Memory*'
```

### System.Memory.Memory<Byte>.ToArray(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Diagnostics.Perf_Process

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

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

| 58.14 ns | 83.62 ns | 1.44 | 0.18 | 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.Diagnostics.Perf_Process*'
```

### System.Diagnostics.Perf_Process.GetCurrentProcess

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

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

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

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

| 226.73 μs | 267.55 μs | 1.18 | 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.Collections.ContainsFalse*'
```

### System.Collections.ContainsFalse<String>.Stack(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Tests.Perf_GC<Char>

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

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

| 48.59 ns | 53.67 ns | 1.10 | 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.Tests.Perf_GC*'
```

### System.Tests.Perf_GC<Char>.AllocateUninitializedArray(length: 1000, pinned: False)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in JetStream.TimeSeriesSegmentation

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

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

| 42.29 ms | 45.46 ms | 1.08 | 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 'JetStream.TimeSeriesSegmentation*'
```

### JetStream.TimeSeriesSegmentation.MaximizeSchwarzCriterion

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

Contributor guide

No contributing guide indexed for this repository

Research direction

Start with the benchmark sources named in src/benchmarks/micro/libraries/System.Collections/Create/CtorGivenSize.cs and src/benchmarks/micro/libraries/System.Threading.Timers/Perf.Timer.cs. Run the provided benchmarks_ci.py command, then compare the reported results with the linked baseline and compare commits. Done means the regressions are reproduced and their cause and next action are recorded.

Written by the indexing model from the issue text.

Assessment

Domain: operating-systems, performance
Issue type: Bug
Difficulty: 4/5
Estimated time: 3-5 days
Activity status: Active
Clarity: Needs clarification
Newbie friendliness: 38/100

[Perf] Windows/x64: 15 Regressions on 8/28/2026 12:45:54 PM +00:00

Description

Contributor guide

Research direction

Assessment

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