Performance improvements for Enum.ToString()

src/mscorlib/src/System/Enum.cs

@@ -137,7 +137,7 @@ private static String InternalFormat(RuntimeType eT, Object value)
             if (!eT.IsDefined(typeof(System.FlagsAttribute), false)) // Not marked with Flags attribute
             {
                 // Try to see if its one of the enum values, then we return a String back else the value
-                String retval = GetName(eT, value);
+                String retval = eT.GetEnumName(value);
                 if (retval == null)
                     return value.ToString();
                 else

src/mscorlib/src/System/Type.cs

@@ -1537,12 +1537,13 @@ public virtual string GetEnumName(object value)
             if (!(valueType.IsEnum || Type.IsIntegerType(valueType)))
                 throw new ArgumentException(Environment.GetResourceString("Arg_MustBeEnumBaseTypeOrEnum"), "value");
 
-            Array values = GetEnumRawConstantValues();
+            string[] names;
+            Array values;
+            GetEnumData(out names, out values);
             int index = BinarySearch(values, value);
 
             if (index >= 0)
             {
-                string[] names = GetEnumNames();
                 return names[index];
             }