# UNDF: UNDF-2026-000000033
diff --git a/Source/cmComputeLinkInformation.cxx b/Source/cmComputeLinkInformation.cxx
index abc1234..def5678 100644
--- a/Source/cmComputeLinkInformation.cxx
+++ b/Source/cmComputeLinkInformation.cxx
@@ -456,14 +456,19 @@ std::vector<BT<std::string>>
 cmComputeLinkInformation::GetDirectoriesWithBacktraces()
 {
   std::vector<BT<std::string>> directoriesWithBacktraces;

   std::vector<BT<std::string>> targetLinkDirectories =
     this->Target->GetLinkDirectories(this->Config, this->LinkLanguage);

+  // Build an index from directory string → BT entry for O(1) lookup.
+  std::unordered_map<std::string, BT<std::string>> dirIndex;
+  dirIndex.reserve(targetLinkDirectories.size());
+  for (auto& bt : targetLinkDirectories)
+    dirIndex.emplace(bt.Value, std::move(bt));
+
   std::vector<std::string> const& orderedDirectories = this->GetDirectories();
   for (std::string const& dir : orderedDirectories) {
-    auto result = std::find(targetLinkDirectories.begin(),
-                            targetLinkDirectories.end(), dir);
-    if (result != targetLinkDirectories.end()) {
-      directoriesWithBacktraces.emplace_back(std::move(*result));
+    auto result = dirIndex.find(dir);
+    if (result != dirIndex.end()) {
+      directoriesWithBacktraces.emplace_back(std::move(result->second));
     } else {
       directoriesWithBacktraces.emplace_back(dir);
     }