[Perf] Windows/x86: 5 Improvements on 5/7/2026 1:08:18 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [055e04bbff528e950acfa0f5e56aa80c2e7929f7](https://github.com/dotnet/runtime/commit/055e04bbff528e950acfa0f5e56aa80c2e7929f7)
Compare | [cdbf0c2ba8a84fdc9d83f019baa2103a0afd580b](https://github.com/dotnet/runtime/commit/cdbf0c2ba8a84fdc9d83f019baa2103a0afd580b)
Diff | [Diff](https://github.com/dotnet/runtime/compare/055e04bbff528e950acfa0f5e56aa80c2e7929f7...cdbf0c2ba8a84fdc9d83f019baa2103a0afd580b)
Configs | CompilationMode:tiered, RunKind:micro

### Improvements in System.Tests.Perf_String

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

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

| 14.76 ns | 13.48 ns | 0.91 | 0.05 | False | | |
|

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

| 14.71 ns | 13.49 ns | 0.92 | 0.03 | False | | |
|

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

| 14.72 ns | 13.53 ns | 0.92 | 0.03 | False | | |
|

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

| 15.01 ns | 13.79 ns | 0.92 | 0.07 | False | | |
|

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

| 55.65 ns | 51.55 ns | 0.93 | 0.03 | False | | |

![graph]()
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[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.Tests.Perf_String*'
```

### System.Tests.Perf_String.ToUpper(s: "TeSt")

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_String.ToLower(s: "TeSt")

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_String.ToUpper(s: "test")

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_String.ToLower(s: "TEST")

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_String.Join_List

#### 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)