Introduce IntKeyedDictionary to improve performance.

Assets/Cryville/Crtr/PropOp.cs

@@ -1,7 +1,7 @@
 using Cryville.Common;
+using Cryville.Common.Collections.Specialized;
 using Cryville.Common.Pdt;
 using System;
-using System.Collections.Generic;
 using System.Reflection;
 using RBeatTime = Cryville.Crtr.BeatTime;
 using RClip = Cryville.Crtr.Clip;
@@ -100,7 +100,7 @@ namespace Cryville.Crtr {
 			}
 		}
 		public class Enum<T> : PropOp {
-			static readonly Dictionary<int, int> _cache = new Dictionary<int, int>();
+			static readonly IntKeyedDictionary<int> _cache = new IntKeyedDictionary<int>();
 			readonly Action<T> _cb;
 			readonly Func<int, T> _caster;
 			static Enum() {
@@ -109,7 +109,6 @@ namespace Cryville.Crtr {
 				var names = typeof(T).GetFields(BindingFlags.Public | BindingFlags.Static);
 				for (int i = 0; i < names.Length; i++)
 					_cache[IdentifierManager.SharedInstance.Request(names[i].Name)] = Convert.ToInt32(names[i].GetValue(null));
-
 			}
 			public Enum(Action<T> cb, Func<int, T> caster) {
 				_cb = cb;