[Perf] Windows/x86: 2 Regressions on 8/28/2026 12:35:59 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [c210d82dbc1ab432b9369604a1caef9a0ab763d2](https://github.com/dotnet/runtime/commit/c210d82dbc1ab432b9369604a1caef9a0ab763d2)
Compare | [57c9c3fdcbc94ad98f0a4b8abedb7c6eadfb264b](https://github.com/dotnet/runtime/commit/57c9c3fdcbc94ad98f0a4b8abedb7c6eadfb264b)
Diff | [Diff](https://github.com/dotnet/runtime/compare/c210d82dbc1ab432b9369604a1caef9a0ab763d2...57c9c3fdcbc94ad98f0a4b8abedb7c6eadfb264b)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Text.RegularExpressions.Tests.Perf_Regex_Industry_RustLang_Sherlock

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

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

| 247.98 μs | 300.48 μs | 1.21 | 0.35 | False | | |
|

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

| 1.80 ms | 1.90 ms | 1.06 | 0.00 | 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.Text.RegularExpressions.Tests.Perf_Regex_Industry_RustLang_Sherlock*'
```

### System.Text.RegularExpressions.Tests.Perf_Regex_Industry_RustLang_Sherlock.Count(Pattern: "the", Options: Compiled)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Text.RegularExpressions.Tests.Perf_Regex_Industry_RustLang_Sherlock.Count(Pattern: "\\p{Lu}", Options: None)

#### 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 src/benchmarks/micro/libraries/System.Text.RegularExpressions/Perf.Regex.Industry.cs lines 193-195 and run the provided benchmarks_ci.py command for the Sherlock filter. Compare the baseline and test commits, then use the linked regression report and profiling workflow to investigate both reported benchmarks. Done means the regressions are explained and the benchmarks no longer show the reported slowdown.

Written by the indexing model from the issue text.