# UNDF: UNDF-2026-000001001
--- a/src/NetPanzer/Units/UnitInterface.hpp
+++ b/src/NetPanzer/Units/UnitInterface.hpp
@@ -1,6 +1,7 @@
 #ifndef _UNITINTERFACE_HPP
 #define _UNITINTERFACE_HPP

+#include <unordered_map>
 #include <map>
 #include <vector>

@@ -44,6 +45,7 @@ class UnitInterface {

  private:
   static Units units;
+  static std::unordered_map<UnitBase*, size_t> playerUnitIndex;
   static PlayerUnitList* playerUnitLists;

   static UnitBucketArray unit_bucket_array;
--- a/src/NetPanzer/Units/UnitInterface.cpp
+++ b/src/NetPanzer/Units/UnitInterface.cpp
@@ -46,6 +46,7 @@
 // UnitList * UnitInterface::unit_lists;
 UnitInterface::Units UnitInterface::units;
 UnitInterface::PlayerUnitList* UnitInterface::playerUnitLists = 0;
+std::unordered_map<UnitBase*, size_t> UnitInterface::playerUnitIndex;
 UnitBucketArray UnitInterface::unit_bucket_array;

 PlayerID UnitInterface::max_players;
@@ -89,6 +90,7 @@ void UnitInterface::cleanUp() {
   for (Units::iterator i = units.begin(); i != units.end(); ++i)
     delete i->second;
   units.clear();
+  playerUnitIndex.clear();
 }

 void UnitInterface::reset() {
@@ -100,6 +102,7 @@ void UnitInterface::reset() {
   for (Units::iterator i = units.begin(); i != units.end(); ++i)
     delete i->second;
   units.clear();
+  playerUnitIndex.clear();
 }

 // ******************************************************************
@@ -165,15 +168,25 @@ void UnitInterface::removeUnit(Units::iterator i) {
   unit_bucket_array.deleteUnitBucketPointer(unit->id,
                                             unit->unit_state.location);
   PlayerUnitList& plist = playerUnitLists[unit->player->getID()];

-  PlayerUnitList::iterator pi = std::find(plist.begin(), plist.end(), unit);
-  assert(pi != plist.end());
-  if (pi != plist.end()) plist.erase(pi);
+  // UNDF: O(1) removal via index map instead of O(U) std::find on vector
+  auto it = playerUnitIndex.find(unit);
+  assert(it != playerUnitIndex.end());
+  if (it != playerUnitIndex.end()) {
+    size_t idx = it->second;
+    if (idx < plist.size() - 1) {
+      UnitBase* back = plist.back();
+      plist[idx] = back;
+      playerUnitIndex[back] = idx;
+    }
+    plist.pop_back();
+    playerUnitIndex.erase(it);
+  }

   units.erase(i);
   delete unit;
 }

 // ******************************************************************
@@ -297,6 +310,7 @@ void UnitInterface::addNewUnit(UnitBase* unit) {
   units.insert(std::make_pair(unit->id, unit));

   Uint16 player_index = unit->player->getID();
+  playerUnitIndex[unit] = playerUnitLists[player_index].size();
   playerUnitLists[player_index].push_back(unit);

   unit_bucket_array.addUnit(unit);