⚡ Optimize string concatenation in OptionCollector

benchmark/Program.cs

@@ -0,0 +1,68 @@
+using System;
+using System.Diagnostics;
+using System.Collections.Generic;
+
+public class Program
+{
+    public static void Main()
+    {
+        var dict = new Dictionary<string, object>();
+        for (int i = 0; i < 50; i++)
+        {
+            dict.Add($"key_{i}", $"value_{i}");
+        }
+
+        // warmup
+        OldWay(dict);
+        NewWay(dict);
+
+        var sw = new Stopwatch();
+
+        sw.Start();
+        for(int i = 0; i < 100000; i++) OldWay(dict);
+        sw.Stop();
+        Console.WriteLine($"Old way: {sw.ElapsedMilliseconds} ms");
+
+        sw.Restart();
+        for(int i = 0; i < 100000; i++) NewWay(dict);
+        sw.Stop();
+        Console.WriteLine($"New way: {sw.ElapsedMilliseconds} ms");
+    }
+
+    public static string OldWay(IDictionary<string, object> dict)
+    {
+        string result = string.Empty;
+        foreach (var item in dict)
+        {
+            object value = item.Value;
+            if (value == null) continue;
+
+            value = $"\\\"{value}\\\"";
+            string key = $"\\\"{item.Key}\\\"";
+            if (string.IsNullOrEmpty(result))
+            {
+                result = $"{key}: {value}";
+            }
+            else
+            {
+                result = result + ", " + key + ": " + value;
+            }
+        }
+        return "\"{" + result + "}\"";
+    }
+
+    public static string NewWay(IDictionary<string, object> dict)
+    {
+        var elements = new List<string>(dict.Count);
+        foreach (var item in dict)
+        {
+            object value = item.Value;
+            if (value == null) continue;
+
+            value = $"\\\"{value}\\\"";
+            string key = $"\\\"{item.Key}\\\"";
+            elements.Add($"{key}: {value}");
+        }
+        return "\"{" + string.Join(", ", elements) + "}\"";
+    }
+}

benchmark/benchmark.csproj

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

src/Appium.Net/Appium/Service/Options/OptionCollector.cs

@@ -78,53 +78,47 @@ public OptionCollector AddCapabilities(AppiumOptions options)
 
         private string ParseCapabilitiesIfWindows()
         {
-            string result = string.Empty;
+            if (options == null)
+            {
+                return "\"{}\"";
+            }
 
-            if (options != null)
+            IDictionary<string, object> capabilitiesDictionary = options.ToDictionary();
+            List<string> result = new List<string>(capabilitiesDictionary.Count);
+
+            foreach (var item in capabilitiesDictionary)
             {
-                IDictionary<string, object> capabilitiesDictionary = options.ToDictionary();
+                object value = item.Value;
 
-                foreach (var item in capabilitiesDictionary)
+                if (value == null)
                 {
-                    object value = item.Value;
-
-                    if (value == null)
-                    {
-                        continue;
-                    }
+                    continue;
+                }
 
-                    if (typeof(string).IsAssignableFrom(value.GetType()))
+                if (typeof(string).IsAssignableFrom(value.GetType()))
+                {
+                    if (AppiumServiceConstants.FilePathCapabilitiesForWindows.Contains(item.Key))
                     {
-                        if (AppiumServiceConstants.FilePathCapabilitiesForWindows.Contains(item.Key))
-                        {
-                            value = $"\\\"{Convert.ToString(value).Replace("\\", "/")}\\\"";
-                        }
-                        else
-                        {
-                            value = $"\\\"{value}\\\"";
-                        }
+                        value = $"\\\"{Convert.ToString(value).Replace("\\", "/")}\\\"";
                     }
                     else
                     {
-                        if (typeof(bool).IsAssignableFrom(value.GetType()))
-                        {
-                            value = Convert.ToString(value).ToLowerInvariant();
-                        }
-                    }
-
-                    string key = $"\\\"{item.Key}\\\"";
-                    if (string.IsNullOrEmpty(result))
-                    {
-                        result = $"{key}: {value}";
+                        value = $"\\\"{value}\\\"";
                     }
-                    else
+                }
+                else
+                {
+                    if (typeof(bool).IsAssignableFrom(value.GetType()))
                     {
-                        result = result + ", " + key + ": " + value;
+                        value = Convert.ToString(value).ToLowerInvariant();
                     }
                 }
+
+                string key = $"\\\"{item.Key}\\\"";
+                result.Add($"{key}: {value}");
             }
 
-            return "\"{" + result + "}\"";
+            return "\"{" + string.Join(", ", result) + "}\"";
         }
 
         private string ParseCapabilitiesIfUNIX()