Reduce memory allocations in NamingStyle.Capitalize/DecapitalizeFirstLetter

src/Workspaces/Core/Portable/NamingStyles/NamingStyle.cs

@@ -88,14 +88,38 @@ private IEnumerable<string> ApplyCapitalization(IEnumerable<string> words)
 
         private string CapitalizeFirstLetter(string word)
         {
+            if (word.Length == 0)
+            {
+                return word;
+            }
+
+            if (char.IsUpper(word[0]))
+            {
+                return word;
+            }
+
             var chars = word.ToCharArray();
-            return new string(chars.Take(1).Select(c => char.ToUpper(c)).Concat(chars.Skip(1)).ToArray());
+            chars[0] = char.ToUpper(chars[0]);
+
+            return new string(chars);
         }
 
         private string DecapitalizeFirstLetter(string word)
         {
+            if (word.Length == 0)
+            {
+                return word;
+            }
+
+            if (char.IsLower(word[0]))
+            {
+                return word;
+            }
+
             var chars = word.ToCharArray();
-            return new string(chars.Take(1).Select(c => char.ToLower(c)).Concat(chars.Skip(1)).ToArray());
+            chars[0] = char.ToLower(chars[0]);
+
+            return new string(chars);
         }
 
         public bool IsNameCompliant(string name, out string failureReason)