Performance benchmark of Catch + When vs Catch + If-Else

benchmark.cs

 [MemoryDiagnoser]
 public class TryCatchWhenBenchmark
 {
     [Params(100, 10_000, 100_000)]
     public int Size;

     [Benchmark]
     public void WithIfElse()
     {
         for (int i = 0; i < Size; i++)
         {

             try
             {
                 if (i % 3 == 0)
                 {
                     throw new ArgumentException(message: "", paramName: "3");
                 }
                 else if (i % 5 == 0)
                 {
                     throw new ArgumentException(message: "", paramName: "5");
                 }
             }
             catch (ArgumentException ex)
             {
                 if (ex.ParamName == "3")
                 {
                     string x = "I am 3";
                 }
                 else if (ex.ParamName == "5")
                 {
                     string x = "I am 5";

                 }
             }
             catch
             {
                 string x = "I am other";

             }
         }
     }

     [Benchmark]
     public void WithWhen()
     {
         for (int i = 0; i < Size; i++)
         {

             try
             {
                 if (i % 3 == 0)
                 {
                     throw new ArgumentException(message: "", paramName: "3");
                 }
                 else if (i % 5 == 0)
                 {
                     throw new ArgumentException(message: "", paramName: "5");
                 }
             }
             catch (ArgumentException ex) when (ex.ParamName == "3")
             {
                 string x = "I am 3";
             }
             catch (ArgumentException ex) when (ex.ParamName == "5")
             {
                 string x = "I am 5";

             }
             catch
             {
                 string x = "I am other";

             }
         }
     }

 }

results.md

BenchmarkDotNet v0.13.11, Windows 11 (10.0.22621.3007/22H2/2022Update/SunValley2) 13th Gen Intel Core i5-1345U, 1 CPU, 12 logical and 10 physical cores .NET SDK 8.0.101 [Host] : .NET 8.0.1 (8.0.123.58001), X64 RyuJIT AVX2 [AttachedDebugger] DefaultJob : .NET 8.0.1 (8.0.123.58001), X64 RyuJIT AVX2

Method	Size	Mean	Error	StdDev	Median	Gen0	Allocated
WithIfElse	100	147.4 us	4.06 us	11.78 us	140.9 us	1.7090	10.65 KB
WithWhen	100	142.6 us	2.80 us	2.87 us	142.5 us	1.7090	10.65 KB
WithIfElse	10000	14,279.8 us	259.62 us	651.33 us	14,127.6 us	171.8750	1057.47 KB
WithWhen	10000	14,238.5 us	193.59 us	171.61 us	14,236.6 us	171.8750	1057.47 KB
WithIfElse	100000	139,117.7 us	2,769.26 us	5,133.00 us	137,155.6 us	1500.0000	10574.62 KB
WithWhen	100000	142,923.5 us	2,785.94 us	3,316.46 us	142,217.0 us	1500.0000	10573.09 KB