# UNDF: UNDF-2026-000001119
--- a/sc/source/filter/excel/xepivotxml.cxx
+++ b/sc/source/filter/excel/xepivotxml.cxx
@@ -1404,16 +1404,22 @@ void XclExpXmlPivotTables::SavePivotTableXml( XclExpXmlStream& rStrm, const ScD
         if (eOrient == sheet::DataPilotFieldOrientation_ROW)
             aRowMemberResultData.initLookupFor(pDim->GetName());
         else if (eOrient == sheet::DataPilotFieldOrientation_COLUMN)
             aColumnMemberResultData.initLookupFor(pDim->GetName());

+        // Build O(1) name-to-index lookup to replace O(C) std::find in the loop below.
+        // Without this map, the loop is O(M * C) where M = aMembers.size() and
+        // C = aCacheFieldItems.size().  Large pivot tables with many distinct values
+        // (e.g. 5000-row data with a text dimension) exhibit quadratic save times.
+        std::unordered_map<OUString, size_t> aCacheItemIndex;
+        aCacheItemIndex.reserve(aCacheFieldItems.size());
+        for (size_t k = 0; k < aCacheFieldItems.size(); ++k)
+            aCacheItemIndex.emplace(aCacheFieldItems[k], k);
+
         // The pair contains the member index in cache and if it is hidden
         std::vector< std::pair<size_t, bool> > aMemberSequence;
         std::set<size_t> aUsedCachePositions;
         sal_Int32 nIndex = 0;
         for (const auto & rMember : aMembers)
         {
-            auto it = std::find(aCacheFieldItems.begin(), aCacheFieldItems.end(), rMember.maName);
-            if (it != aCacheFieldItems.end())
+            auto mapIt = aCacheItemIndex.find(rMember.maName);
+            if (mapIt != aCacheItemIndex.end())
             {
-                size_t nCachePos = static_cast<size_t>(std::distance(aCacheFieldItems.begin(), it));
+                size_t nCachePos = mapIt->second;
                 auto aInserted = aUsedCachePositions.insert(nCachePos);
                 if (aInserted.second)
                 {