[Perf] Linux/x64: 2 Improvements on 7/22/2026 8:34:21 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [5ffdd753b0146f0ec95786b2af0ab7da0b37d061](https://github.com/dotnet/runtime/commit/5ffdd753b0146f0ec95786b2af0ab7da0b37d061)
Compare | [57f3e7eaec55cf263674f65eabb8965b612dc997](https://github.com/dotnet/runtime/commit/57f3e7eaec55cf263674f65eabb8965b612dc997)
Diff | [Diff](https://github.com/dotnet/runtime/compare/5ffdd753b0146f0ec95786b2af0ab7da0b37d061...57f3e7eaec55cf263674f65eabb8965b612dc997)
Configs | AOT:true, CompilationMode:wasm, RunKind:micro

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

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

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

| 12.74 μs | 11.76 μs | 0.92 | 0.07 | False | | |
|

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

| 12.46 μs | 11.67 μs | 0.94 | 0.08 | 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.Globalization.Tests.StringSearch*'
```

### System.Globalization.Tests.StringSearch.LastIndexOf_Word_NotFound(Options: (en-US, IgnoreCase, True))

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Globalization.Tests.StringSearch.LastIndexOf_Word_NotFound(Options: (en-US, None, True))

#### 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 dotnet/performance/src/benchmarks/micro/libraries/System.Globalization/StringSearch.cs#L106-L108 and the benchmarking workflow linked in the issue. Run the provided benchmarks_ci.py command with the System.Globalization.Tests.StringSearch filter under the reported AOT/WebAssembly configuration, then compare the result with the linked report. Done means confirming whether the improvement reproduces and identifying an actionable cause or follow-up.

Written by the indexing model from the issue text.