[Perf] Linux/x64: 5 Regressions on 8/22/2026 2:29:58 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [76c60b960a2daa412c44a5061abf66f3286f6a92](https://github.com/dotnet/runtime/commit/76c60b960a2daa412c44a5061abf66f3286f6a92)
Compare | [75cffcef7186a6a0b738f15a98d0b28c6c8e6507](https://github.com/dotnet/runtime/commit/75cffcef7186a6a0b738f15a98d0b28c6c8e6507)
Diff | [Diff](https://github.com/dotnet/runtime/compare/76c60b960a2daa412c44a5061abf66f3286f6a92...75cffcef7186a6a0b738f15a98d0b28c6c8e6507)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

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

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

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

| 1.80 μs | 2.47 μs | 1.37 | 0.32 | False | | |
|

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

| 4.86 μs | 5.66 μs | 1.16 | 0.20 | 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
python3 .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Buffers.Tests.ReadOnlySequenceTests*'
```

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

#### ETL Files

#### Histogram

#### JIT Disasms

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

#### 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 | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [76c60b960a2daa412c44a5061abf66f3286f6a92](https://github.com/dotnet/runtime/commit/76c60b960a2daa412c44a5061abf66f3286f6a92)
Compare | [75cffcef7186a6a0b738f15a98d0b28c6c8e6507](https://github.com/dotnet/runtime/commit/75cffcef7186a6a0b738f15a98d0b28c6c8e6507)
Diff | [Diff](https://github.com/dotnet/runtime/compare/76c60b960a2daa412c44a5061abf66f3286f6a92...75cffcef7186a6a0b738f15a98d0b28c6c8e6507)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

### Regressions in System.Collections.Perf_LengthBucketsFrozenDictionary

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

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

| 19.35 μs | 21.66 μs | 1.12 | 0.28 | False | | |
|

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

| 21.21 μs | 22.91 μs | 1.08 | 0.28 | 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
python3 .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Collections.Perf_LengthBucketsFrozenDictionary*'
```

### System.Collections.Perf_LengthBucketsFrozenDictionary.ToFrozenDictionary(Count: 10, ItemsPerBucket: 5)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Collections.Perf_LengthBucketsFrozenDictionary.ToFrozenDictionary(Count: 10, ItemsPerBucket: 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

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [129ada6e62fb997068c4151f69ecb3e39fb6f4be](https://github.com/dotnet/runtime/commit/129ada6e62fb997068c4151f69ecb3e39fb6f4be)
Compare | [75cffcef7186a6a0b738f15a98d0b28c6c8e6507](https://github.com/dotnet/runtime/commit/75cffcef7186a6a0b738f15a98d0b28c6c8e6507)
Diff | [Diff](https://github.com/dotnet/runtime/compare/129ada6e62fb997068c4151f69ecb3e39fb6f4be...75cffcef7186a6a0b738f15a98d0b28c6c8e6507)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

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

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

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

| 1.66 ms | 2.48 ms | 1.49 | 0.33 | 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
python3 .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Collections.AddGivenSize*'
```

### System.Collections.AddGivenSize<String>.ObservableCollection(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 with the benchmark entries and the linked source at src/benchmarks/micro/libraries/System.Buffers/ReadOnlySequenceTests.cs, then run the documented benchmarks_ci.py filters on Ubuntu 22.04. Compare the reported results with the baseline and investigate the listed regressions; done means the cause is identified and the affected benchmarks no longer regress.

Written by the indexing model from the issue text.