[Perf] Windows/x86: 2 Regressions on 9/3/2026 6:36:03 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [a4ec83ce5eb429ae06d11ac13b1881eaf6651b1c](https://github.com/dotnet/runtime/commit/a4ec83ce5eb429ae06d11ac13b1881eaf6651b1c)
Compare | [25f20c2fd360fc0d7c126e50f7c784f8338d6faf](https://github.com/dotnet/runtime/commit/25f20c2fd360fc0d7c126e50f7c784f8338d6faf)
Diff | [Diff](https://github.com/dotnet/runtime/compare/a4ec83ce5eb429ae06d11ac13b1881eaf6651b1c...25f20c2fd360fc0d7c126e50f7c784f8338d6faf)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Collections.CopyTo<Int32>

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

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

| 214.16 ns | 2284.60 ns | 10.67 | 0.21 | False | | |
|

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

| 201.54 ns | 229.11 ns | 1.14 | 0.26 | 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.Collections.CopyTo*'
```

### System.Collections.CopyTo<Int32>.List(Size: 2048)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Collections.CopyTo<Int32>.Array(Size: 2048)

#### 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.Collections/CopyTo.cs lines 33-34 and 59-60, then run the provided benchmarks_ci.py command. Compare the listed baseline and test commits and use the linked reports to investigate both CopyTo regressions; done means the cause is identified and the regression is addressed.

Written by the indexing model from the issue text.