Index: src/main/java/org/apache/jackrabbit/oak/segment/Segment.java
===================================================================
--- src/main/java/org/apache/jackrabbit/oak/segment/Segment.java	(revision 1764212)
+++ src/main/java/org/apache/jackrabbit/oak/segment/Segment.java	(working copy)
@@ -218,51 +218,82 @@
         }
     }
 
+    private RecordNumbers cachedRecordNumbers;
+
+    private final Object cachedRecordNumbersLock = new Object();
+
     /**
      * Read the serialized table mapping record numbers to offsets.
      *
      * @return An instance of {@link RecordNumbers}, never {@code null}.
      */
     private RecordNumbers readRecordNumberOffsets() {
-        Map<Integer, RecordEntry> recordNumberOffsets = newLinkedHashMap();
+        if (cachedRecordNumbers != null) {
+            return cachedRecordNumbers;
+        }
 
-        int position = data.position();
+        synchronized (cachedRecordNumbersLock) {
+            if (cachedRecordNumbers != null) {
+                return cachedRecordNumbers;
+            }
 
-        position += HEADER_SIZE;
-        position += getReferencedSegmentIdCount() * SEGMENT_REFERENCE_SIZE;
+            Map<Integer, RecordEntry> recordNumberOffsets = newLinkedHashMap();
 
-        for (int i = 0; i < getRecordNumberCount(); i++) {
-            int recordNumber = data.getInt(position);
-            position += 4;
-            int type = data.get(position);
-            position += 1;
-            int offset = data.getInt(position);
-            position += 4;
-            recordNumberOffsets.put(recordNumber, new RecordEntry(RecordType.values()[type], offset));
+            int position = data.position();
+
+            position += HEADER_SIZE;
+            position += getReferencedSegmentIdCount() * SEGMENT_REFERENCE_SIZE;
+
+            for (int i = 0; i < getRecordNumberCount(); i++) {
+                int recordNumber = data.getInt(position);
+                position += 4;
+                int type = data.get(position);
+                position += 1;
+                int offset = data.getInt(position);
+                position += 4;
+                recordNumberOffsets.put(recordNumber, new RecordEntry(RecordType.values()[type], offset));
+            }
+
+            cachedRecordNumbers = new ImmutableRecordNumbers(recordNumberOffsets);
         }
 
-        return new ImmutableRecordNumbers(recordNumberOffsets);
+        return cachedRecordNumbers;
     }
 
+    private SegmentReferences cachedSegmentReferences;
+
+    private final Object cachedSegmentReferencesLock = new Object();
+
     private SegmentReferences readReferencedSegments() {
-        checkState(getReferencedSegmentIdCount() + 1 < 0xffff,
-                "Segment cannot have more than 0xffff references");
+        if (cachedSegmentReferences != null) {
+            return cachedSegmentReferences;
+        }
 
-        List<SegmentId> referencedSegments = newArrayListWithCapacity(getReferencedSegmentIdCount());
+        synchronized (cachedSegmentReferencesLock) {
+            if (cachedSegmentReferences != null) {
+                return cachedSegmentReferences;
+            }
 
-        int position = data.position();
+            checkState(getReferencedSegmentIdCount() + 1 < 0xffff, "Segment cannot have more than 0xffff references");
 
-        position += HEADER_SIZE;
+            List<SegmentId> referencedSegments = newArrayListWithCapacity(getReferencedSegmentIdCount());
 
-        for (int i = 0; i < getReferencedSegmentIdCount(); i++) {
-            long msb = data.getLong(position);
-            position += 8;
-            long lsb = data.getLong(position);
-            position += 8;
-            referencedSegments.add(store.newSegmentId(msb, lsb));
+            int position = data.position();
+
+            position += HEADER_SIZE;
+
+            for (int i = 0; i < getReferencedSegmentIdCount(); i++) {
+                long msb = data.getLong(position);
+                position += 8;
+                long lsb = data.getLong(position);
+                position += 8;
+                referencedSegments.add(store.newSegmentId(msb, lsb));
+            }
+
+            cachedSegmentReferences = new ImmutableSegmentReferences(referencedSegments);
         }
 
-        return new ImmutableSegmentReferences(referencedSegments);
+        return cachedSegmentReferences;
     }
 
     Segment(@Nonnull SegmentStore store,