[Perf] Windows/x86: 2 Improvements on 6/26/2026 6:28:17 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [22c1ced1d71c05e96f9cca3c2d6171ba9e5f0a55](https://github.com/dotnet/runtime/commit/22c1ced1d71c05e96f9cca3c2d6171ba9e5f0a55)
Compare | [207ffd155f96b38be1749584b99f3ac0a505218c](https://github.com/dotnet/runtime/commit/207ffd155f96b38be1749584b99f3ac0a505218c)
Diff | [Diff](https://github.com/dotnet/runtime/compare/22c1ced1d71c05e96f9cca3c2d6171ba9e5f0a55...207ffd155f96b38be1749584b99f3ac0a505218c)
Configs | CompilationMode:tiered, RunKind:micro

### Improvements in System.Memory.Span<Int32>

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

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

| 97.91 ns | 89.12 ns | 0.91 | 0.09 | 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.Span*'
```

### System.Memory.Span<Int32>.StartsWith(Size: 3000)

#### 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 | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [22c1ced1d71c05e96f9cca3c2d6171ba9e5f0a55](https://github.com/dotnet/runtime/commit/22c1ced1d71c05e96f9cca3c2d6171ba9e5f0a55)
Compare | [207ffd155f96b38be1749584b99f3ac0a505218c](https://github.com/dotnet/runtime/commit/207ffd155f96b38be1749584b99f3ac0a505218c)
Diff | [Diff](https://github.com/dotnet/runtime/compare/22c1ced1d71c05e96f9cca3c2d6171ba9e5f0a55...207ffd155f96b38be1749584b99f3ac0a505218c)
Configs | CompilationMode:tiered, RunKind:micro

### Improvements in System.Buffers.Tests.SearchValuesCharTests

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

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

| 101.08 ns | 89.34 ns | 0.88 | 0.01 | 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.SearchValuesCharTests*'
```

### System.Buffers.Tests.SearchValuesCharTests.LastIndexOfAnyExcept(Values: "ßäöüÄÖÜ")

#### 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 src/benchmarks/micro/libraries/System.Memory/Span.cs and src/benchmarks/micro/libraries/System.Buffers/SearchValuesCharTests.cs, then run the two benchmark commands in the issue. Compare the reports with the linked baseline and compare commits, and establish whether the reported improvements are reproducible and what follow-up is needed.

Written by the indexing model from the issue text.