perf

name	perf
description	Performance optimization with benchmarking first. Use when asked to optimize, improve speed, reduce allocations, or profile code.
disable-model-invocation	true
argument-hint	<class.method to optimize>

You are tasked with optimizing the performance of: $ARGUMENTS

Follow this workflow in order:

1. Create a BenchmarkDotNet benchmark file:

   • Path: PhotoManager/Benchmarks/PhotoManager.Benchmarks/{Category}/{ClassName}{MethodName}Benchmarks.cs
   • Example: PhotoManager/Benchmarks/PhotoManager.Benchmarks/Common/HashingHelperCalculateHashBenchmarks.cs
   • Use attributes: [MemoryDiagnoser], [Orderer(SummaryOrderPolicy.FastestToSlowest)], [RankColumn]
   • Mark the CURRENT implementation as [Benchmark(Baseline = true)]

2. Keep the original method unchanged in its source file — do NOT modify it yet.

3. Add optimized implementations IN THE BENCHMARK FILE ONLY:

   • Each optimization gets its own [Benchmark] method
   • Name them clearly: Optimized_ApproachName, Optimized_Stackalloc, etc.

4. Run the benchmark:

   dotnet run --project PhotoManager/Benchmarks/PhotoManager.Benchmarks/PhotoManager.Benchmarks.csproj -c Release -- --filter "*BenchmarkClassName"
   

5. Evaluate results (speed is priority, but allocation shouldn't increase significantly):

   • Speed: Lower Mean/Median is better
   • Memory: Lower Allocated is better
   • Check the Ratio column compared to baseline

6. Implement the winner in the original source file:

   • Replace ONLY if there's clear improvement
   • Add comment: // ClassName.MethodName: X% faster
   • Check GlobalUsings.cs before adding any using directives

7. Verify: Run dotnet test --filter "FullyQualifiedName~ClassName" PhotoManager/PhotoManager.slnx to ensure no regressions. Build must produce zero warnings.

8. Keep all variants in the benchmark file (original + all optimizations) for future reference.

Return benchmark results summary with percentage improvement.