diff --git a/src/Interfaces/IHistoryState.ts b/src/Interfaces/IHistoryState.ts
index c0d8214..3576c2a 100644
--- a/src/Interfaces/IHistoryState.ts
+++ b/src/Interfaces/IHistoryState.ts
@@ -8,6 +8,10 @@ export interface IHistoryState {
   /** Reference to the main container */
   mainContainer: IContainerModel
 
+  // TODO: Add hashmap<string, IContainerModel> to optimize FincContainerById from worst O(n) to O(1)
+  // TODO: this hashmap will not be serialized, modify it in the replacer and reviver in saveload.ts + worker.js
+  // TODO: Update addContainers and deleteContainer to update the hashmap
+
   /** Id of the selected container */
   selectedContainerId: string