# UNDF: UNDF-2026-000001002
--- a/src/NetPanzer/Units/UnitBucketArray.hpp
+++ b/src/NetPanzer/Units/UnitBucketArray.hpp
@@ -1,6 +1,7 @@
 #ifndef _UNIT_BUCKET_ARRAY_HPP
 #define _UNIT_BUCKET_ARRAY_HPP

+#include <unordered_map>
 #include "ArrayUtil/BucketArrayTemplate.hpp"
 #include "Units/UnitBase.hpp"

@@ -47,6 +48,9 @@ class UnitBucketArray : public UnitBucketArrayTemplate {
   iXY map_size;
   long map_size_x;
   long map_size_y;
+
+  // UNDF: O(1) unit-to-bucket lookup instead of O(B*U) full scan
+  std::unordered_map<UnitID, unsigned long> unitBucketMap;
   iXY tile_size;

  public:
--- a/src/NetPanzer/Units/UnitBucketArray.cpp
+++ b/src/NetPanzer/Units/UnitBucketArray.cpp
@@ -107,6 +107,7 @@ void UnitBucketArray::addUnit(UnitBase *unit) {

   unit_bucket_ptr = new UnitBucketPointer(unit);

+  unitBucketMap[unit->id] = bucket_index;
   array[bucket_index].addFront(unit_bucket_ptr);
 }

@@ -119,25 +120,20 @@ void UnitBucketArray::addUnit(UnitBucketPointer *unit_bucket_ptr) {

   assert(bucket_index < (long)size);

+  unitBucketMap[unit->id] = bucket_index;
   array[bucket_index].addFront(unit_bucket_ptr);
 }

 long UnitBucketArray::getUnitBucketIndex(UnitID unit_id) {
-  for (unsigned long bucket_index = 0; bucket_index < size; bucket_index++) {
-    UnitBucketPointer *traversal_ptr;
-
-    traversal_ptr = array[bucket_index].getFront();
-
-    while (traversal_ptr != 0) {
-      if (traversal_ptr->unit->id == unit_id) return (long)bucket_index;
-
-      traversal_ptr = traversal_ptr->next;
-    }
+  // UNDF: O(1) lookup via hash map instead of O(B*U) full bucket scan
+  auto it = unitBucketMap.find(unit_id);
+  if (it != unitBucketMap.end()) {
+    return (long)it->second;
   }
-
   return -1;
 }

@@ -207,6 +203,7 @@ bool UnitBucketArray::moveUnit(UnitID unit_id, unsigned long from_bucket_index,
       move_ptr = traversal_ptr;
       traversal_ptr = traversal_ptr->next;
       array[from_bucket_index].removeObject(move_ptr);
+      unitBucketMap[unit_id] = to_bucket_index;
       array[to_bucket_index].addFront(move_ptr);
       found = true;
     } else {
@@ -241,6 +238,7 @@ bool UnitBucketArray::deleteUnitBucketPointer(UnitID unit_id, iXY world_loc) {
   while (traversal_ptr != 0) {
     if (traversal_ptr->unit->id == unit_id) {
       array[bucket_index].deleteObject(traversal_ptr);
+      unitBucketMap.erase(unit_id);
       return true;
     }