[Perf] Linux/x64: 2 Regressions on 6/25/2026 4:49:37 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [ce71db3201f610d5a8cbf692cc3081f8784992fc](https://github.com/dotnet/runtime/commit/ce71db3201f610d5a8cbf692cc3081f8784992fc)
Compare | [42f3669b3a7f418f571ad63a77b3e7ebf9ee64a8](https://github.com/dotnet/runtime/commit/42f3669b3a7f418f571ad63a77b3e7ebf9ee64a8)
Diff | [Diff](https://github.com/dotnet/runtime/compare/ce71db3201f610d5a8cbf692cc3081f8784992fc...42f3669b3a7f418f571ad63a77b3e7ebf9ee64a8)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

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

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

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

| 33.18 ms | 41.48 ms | 1.25 | 0.36 | 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.CreateAddAndRemove*'
```

### System.Collections.CreateAddAndRemove<String>.SortedList(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

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [ce71db3201f610d5a8cbf692cc3081f8784992fc](https://github.com/dotnet/runtime/commit/ce71db3201f610d5a8cbf692cc3081f8784992fc)
Compare | [42f3669b3a7f418f571ad63a77b3e7ebf9ee64a8](https://github.com/dotnet/runtime/commit/42f3669b3a7f418f571ad63a77b3e7ebf9ee64a8)
Diff | [Diff](https://github.com/dotnet/runtime/compare/ce71db3201f610d5a8cbf692cc3081f8784992fc...42f3669b3a7f418f571ad63a77b3e7ebf9ee64a8)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

### Regressions in Benchstone.BenchF.LLoops

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

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

| 19.31 secs | 20.96 secs | 1.09 | 0.22 | 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 'Benchstone.BenchF.LLoops*'
```

### Benchstone.BenchF.LLoops.Test

#### 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 sources at src/benchmarks/micro/libraries/System.Collections/CreateAddAndRemove.cs#L86-L99 and src/benchmarks/micro/runtime/Benchstones/BenchF/LLoops.cs#L135-L157, then run the provided benchmarks_ci.py commands. Compare the reported baseline and test results for both regressions, and verify that the performance regression is understood and no longer reproduced.

Written by the indexing model from the issue text.