[Perf] Linux/arm64: 2 Improvements on 7/1/2026 9:59:07 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [88e2ee68affb2e6e71727630df8833dced0875f4](https://github.com/dotnet/runtime/commit/88e2ee68affb2e6e71727630df8833dced0875f4)
Compare | [2ca5bd514647fe0e961dd237dc9af0004479da6f](https://github.com/dotnet/runtime/commit/2ca5bd514647fe0e961dd237dc9af0004479da6f)
Diff | [Diff](https://github.com/dotnet/runtime/compare/88e2ee68affb2e6e71727630df8833dced0875f4...2ca5bd514647fe0e961dd237dc9af0004479da6f)
Configs | CompilationMode:tiered, RunKind:micro

### Improvements in System.Globalization.Tests.StringSearch

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

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

| 43.76 ns | 34.87 ns | 0.80 | 0.22 | False | | |
|

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

| 81.78 ns | 66.34 ns | 0.81 | 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
py .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Globalization.Tests.StringSearch*'
```

### System.Globalization.Tests.StringSearch.IsPrefix_FirstHalf(Options: (en-US, OrdinalIgnoreCase, False))

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Globalization.Tests.StringSearch.IsSuffix_DifferentLastChar(Options: (en-US, OrdinalIgnoreCase, False))

#### 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 source at performance/src/benchmarks/micro/libraries/System.Globalization/StringSearch.cs lines 87-88 and 98-100, then run the provided benchmarks_ci.py command for System.Globalization.Tests.StringSearch. Compare the reported ARM64 AzureLinux results and profiling reports; done requires a clearly justified runtime performance change or confirmation that no code change is warranted.

Written by the indexing model from the issue text.