diff --git a/Scripts/NodeDataCache.cs b/Scripts/NodeDataCache.cs
index e05d033..7061f17 100644
--- a/Scripts/NodeDataCache.cs
+++ b/Scripts/NodeDataCache.cs
@@ -7,6 +7,7 @@ namespace XNode {
     /// <summary> Precaches reflection data in editor so we won't have to do it runtime </summary>
     public static class NodeDataCache {
         private static PortDataCache portDataCache;
+        private static Dictionary<System.Type, Dictionary<string, string>> formerlySerializedAsCache;
         private static bool Initialized { get { return portDataCache != null; } }
 
         /// <summary> Update static ports and dynamic ports managed by DynamicPortLists to reflect class fields. </summary>
@@ -14,10 +15,12 @@ namespace XNode {
             if (!Initialized) BuildCache();
 
             Dictionary<string, NodePort> staticPorts = new Dictionary<string, NodePort>();
-            Dictionary<string, string> formerlySerializedAs = new Dictionary<string, string>();
             Dictionary<string, List<NodePort>> removedPorts = new Dictionary<string, List<NodePort>>();
             System.Type nodeType = node.GetType();
 
+            Dictionary<string, string> formerlySerializedAs = null;
+            if (formerlySerializedAsCache != null) formerlySerializedAsCache.TryGetValue(nodeType, out formerlySerializedAs);
+
             List<NodePort> dynamicListPorts = new List<NodePort>();
 
             List<NodePort> typePortCache;
@@ -25,11 +28,6 @@ namespace XNode {
                 for (int i = 0; i < typePortCache.Count; i++) {
                     staticPorts.Add(typePortCache[i].fieldName, portDataCache[nodeType][i]);
                 }
-                for (int i = 0; i < typePortCache.Count; i++) {
-                    var fieldInfo = nodeType.GetField(typePortCache[i].fieldName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
-                    var attribute = fieldInfo.GetCustomAttributes(true).FirstOrDefault(x => x is UnityEngine.Serialization.FormerlySerializedAsAttribute) as UnityEngine.Serialization.FormerlySerializedAsAttribute;
-                    if (attribute != null) formerlySerializedAs.Add(attribute.oldName, typePortCache[i].fieldName);
-                }
             }
 
             // Cleanup port dict - Remove nonexisting static ports - update static port types
@@ -52,7 +50,7 @@ namespace XNode {
                     //See if the field is tagged with FormerlySerializedAs, if so add the port with its new field name to removedPorts
                     // so it can be reconnected in missing ports stage.
                     string newName = null;
-                    if (formerlySerializedAs.TryGetValue(port.fieldName, out newName)) removedPorts.Add(newName, port.GetConnections());
+                    if (formerlySerializedAs != null && formerlySerializedAs.TryGetValue(port.fieldName, out newName)) removedPorts.Add(newName, port.GetConnections());
 
                     port.ClearConnections();
                     ports.Remove(port.fieldName);
@@ -188,6 +186,7 @@ namespace XNode {
                 object[] attribs = fieldInfo[i].GetCustomAttributes(true);
                 Node.InputAttribute inputAttrib = attribs.FirstOrDefault(x => x is Node.InputAttribute) as Node.InputAttribute;
                 Node.OutputAttribute outputAttrib = attribs.FirstOrDefault(x => x is Node.OutputAttribute) as Node.OutputAttribute;
+                UnityEngine.Serialization.FormerlySerializedAsAttribute formerlySerializedAsAttribute = attribs.FirstOrDefault(x => x is UnityEngine.Serialization.FormerlySerializedAsAttribute) as UnityEngine.Serialization.FormerlySerializedAsAttribute;
 
                 if (inputAttrib == null && outputAttrib == null) continue;
 
@@ -196,6 +195,12 @@ namespace XNode {
                     if (!portDataCache.ContainsKey(nodeType)) portDataCache.Add(nodeType, new List<NodePort>());
                     portDataCache[nodeType].Add(new NodePort(fieldInfo[i]));
                 }
+
+                if(formerlySerializedAsAttribute != null) {
+                    if (formerlySerializedAsCache == null) formerlySerializedAsCache = new Dictionary<System.Type, Dictionary<string, string>>();
+                    if (!formerlySerializedAsCache.ContainsKey(nodeType)) formerlySerializedAsCache.Add(nodeType, new Dictionary<string, string>());
+                    formerlySerializedAsCache[nodeType].Add(formerlySerializedAsAttribute.oldName, fieldInfo[i].Name);
+                }
             }
         }