diff --git a/api/src/org/labkey/api/assay/AbstractAssayTsvDataHandler.java b/api/src/org/labkey/api/assay/AbstractAssayTsvDataHandler.java
index f8f3f3b2158..421183f59d7 100644
--- a/api/src/org/labkey/api/assay/AbstractAssayTsvDataHandler.java
+++ b/api/src/org/labkey/api/assay/AbstractAssayTsvDataHandler.java
@@ -121,6 +121,7 @@
 import java.util.Objects;
 import java.util.Set;
 import java.util.function.Function;
+import java.util.stream.Collectors;
 
 import static java.util.stream.Collectors.toList;
 import static org.labkey.api.assay.AssayRunUploadContext.ReImportOption.MERGE_DATA;
@@ -1084,13 +1085,27 @@ else if (validatorMap.containsKey(pd))
 
                     if (plateId != null && wellLocation != null)
                     {
-                        Map<String, Long> wellSampleCache = plateWellCache.computeIfAbsent(plateId, (id) -> AssayPlateMetadataService.get().getWellLocationToSampleIdMap(container, user, plateId));
+                        boolean loadMaterialsCache = !plateWellCache.containsKey(plateId);
+                        Map<String, Long> wellSampleCache = plateWellCache.computeIfAbsent(plateId, (id) -> AssayPlateMetadataService.get().getWellLocationToSampleIdMap(plateId));
+
+                        // If we had to load the wellSampleCache we should also preload the ExpMaterials into the
+                        // materialCache, so we don't need to fetch them with individual queries. This has a large
+                        // impact on performance.
+                        if (loadMaterialsCache)
+                        {
+                            Set<Long> samplesToFetch = wellSampleCache.values().stream()
+                                    .filter(id -> !materialCache.containsKey(id))
+                                    .collect(Collectors.toSet());
+
+                            for (ExpMaterial m : exp.getExpMaterials(samplesToFetch))
+                                materialCache.put(m.getRowId(), m);
+                        }
                         sampleId = wellSampleCache.get(wellLocation);
                     }
 
                     if (sampleId != null)
                     {
-                        material = materialCache.computeIfAbsent(sampleId, (id) -> exp.getExpMaterial(id, containerFilter));
+                        material = materialCache.get(sampleId);
                     }
 
                     if (material != null)
diff --git a/api/src/org/labkey/api/assay/plate/AssayPlateMetadataService.java b/api/src/org/labkey/api/assay/plate/AssayPlateMetadataService.java
index 1f35bd5c560..f4b60adb492 100644
--- a/api/src/org/labkey/api/assay/plate/AssayPlateMetadataService.java
+++ b/api/src/org/labkey/api/assay/plate/AssayPlateMetadataService.java
@@ -187,7 +187,7 @@ void applyHitSelectionCriteria(
     /**
      * Returns a Map of Well Location to Sample RowID for a given Plate ID.
      */
-    Map<String, Long> getWellLocationToSampleIdMap(Container container, User user, Long plateId);
+    Map<String, Long> getWellLocationToSampleIdMap(Long plateId);
 
     boolean isWellLookup(ColumnInfo col);
 
diff --git a/assay/src/org/labkey/assay/plate/AssayPlateMetadataServiceImpl.java b/assay/src/org/labkey/assay/plate/AssayPlateMetadataServiceImpl.java
index 66f37dc79ca..0f6091a0f74 100644
--- a/assay/src/org/labkey/assay/plate/AssayPlateMetadataServiceImpl.java
+++ b/assay/src/org/labkey/assay/plate/AssayPlateMetadataServiceImpl.java
@@ -1518,14 +1518,23 @@ public String format(FieldKey fieldKey)
         return new PlateSchema(querySchema, contextualRoles);
     }
 
+    record WellSampleData(Long sampleId, Integer row, Integer col) {}
+
     @Override
-    public Map<String, Long> getWellLocationToSampleIdMap(Container container, User user, Long plateId)
+    public Map<String, Long> getWellLocationToSampleIdMap(Long plateId)
     {
+        // Note: this method intentionally does not use PlateManager.get().getWellData, by selecting only the columns
+        // we need there is a small but measurable performance boost when importing plate assay data
+        SimpleFilter filter = new SimpleFilter(WellTable.Column.PlateId.fieldKey(), plateId);
+        Set<String> columns = Set.of(WellTable.Column.SampleID.name(), WellTable.Column.Row.name(), WellTable.Column.Col.name());
+        List<WellSampleData> wells = new TableSelector(AssayDbSchema.getInstance().getTableInfoWell(), columns, filter, null).getArrayList(WellSampleData.class);
         Map<String, Long> wellLocationToSampleIdMap = new HashMap<>();
-        List<WellData> wellData = PlateManager.get().getWellData(container, user, plateId, true, false);
 
-        for (WellData data : wellData)
-            wellLocationToSampleIdMap.put(data.getPosition(), data.getSampleId());
+        for (WellSampleData well : wells)
+        {
+            PositionImpl pos = new PositionImpl(null, well.row, well.col);
+            wellLocationToSampleIdMap.put(pos.getDescription(), well.sampleId);
+        }
 
         return wellLocationToSampleIdMap;
     }