[Perf] Windows/x64: 1 Improvement on 8/7/2026 9:57:17 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [9bf3be3ad48e77e97436fa96825cb713a6964389](https://github.com/dotnet/runtime/commit/9bf3be3ad48e77e97436fa96825cb713a6964389)
Compare | [7da460b99b9c7e76b3060ef6da6687a008263ab9](https://github.com/dotnet/runtime/commit/7da460b99b9c7e76b3060ef6da6687a008263ab9)
Diff | [Diff](https://github.com/dotnet/runtime/compare/9bf3be3ad48e77e97436fa96825cb713a6964389...7da460b99b9c7e76b3060ef6da6687a008263ab9)
Configs | CompilationMode:tiered, RunKind:micro

### Improvements in System.Collections.Tests.Perf_BitArray

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

• [BitArrayAnd - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config 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.Tests.Perf_BitArray*'
```

### System.Collections.Tests.Perf_BitArray.BitArrayAnd(Size: 512)

#### 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.Collections/Perf.BitArray.cs at lines 99-100 and run the supplied benchmarks_ci.py command for System.Collections.Tests.Perf_BitArray. Review the linked benchmark and comparison reports to understand the BitArrayAnd improvement on Windows x64. Done should include a justified performance change or a documented explanation supported by benchmark results.

Written by the indexing model from the issue text.