[Perf] Linux/x64: 2 Regressions on 8/4/2026 3:42:07 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [80aa3f8c5a2d33664fbedafd2f2bb18fdeb8002f](https://github.com/dotnet/runtime/commit/80aa3f8c5a2d33664fbedafd2f2bb18fdeb8002f)
Compare | [f107b2325cccfd453f9bf46013159f4704ea56c2](https://github.com/dotnet/runtime/commit/f107b2325cccfd453f9bf46013159f4704ea56c2)
Diff | [Diff](https://github.com/dotnet/runtime/compare/80aa3f8c5a2d33664fbedafd2f2bb18fdeb8002f...f107b2325cccfd453f9bf46013159f4704ea56c2)
Configs | CompilationMode:wasm, RunKind:micro

### Regressions in System.Tests.Perf_Double

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

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

| 502.46 μs | 534.75 μs | 1.06 | 0.01 | False | | |
|

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

| 505.12 μs | 532.01 μs | 1.05 | 0.02 | 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.Tests.Perf_Double*'
```

### System.Tests.Perf_Double.ToStringWithFormat(value: 1.7976931348623157E+308, format: "F50")

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_Double.ToStringWithFormat(value: -1.7976931348623157E+308, format: "F50")

#### 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.Runtime/Perf.Double.cs#L65-L69 and run the provided benchmarks_ci.py command for System.Tests.Perf_Double. Compare the two ToStringWithFormat cases against the listed baseline and compare commits, then inspect the linked reports and profiling workflow. Done means identifying and addressing the regression, with the benchmark timings no longer showing the reported slowdown.

Written by the indexing model from the issue text.