diff --git a/lucene/contrib/CHANGES.txt b/lucene/contrib/CHANGES.txt
index 9c0b3e1d6ef..3c646719681 100644
--- a/lucene/contrib/CHANGES.txt
+++ b/lucene/contrib/CHANGES.txt
@@ -200,6 +200,9 @@ Bug Fixes
  * LUCENE-3697: SimpleBoundaryScanner does not work well when highlighting
    at the beginning of the text. (Shay Banon via Koji Sekiguchi)
 
+ * LUCENE-3719: FVH: slow performance on very large queries.
+   (Igor Motov via Koji Sekiguchi)
+
 Documentation
 
  * LUCENE-3599: Javadocs for DistanceUtils.haversine() were incorrectly
diff --git a/lucene/contrib/highlighter/src/java/org/apache/lucene/search/vectorhighlight/FieldQuery.java b/lucene/contrib/highlighter/src/java/org/apache/lucene/search/vectorhighlight/FieldQuery.java
index e329136647c..c5f8d76de46 100644
--- a/lucene/contrib/highlighter/src/java/org/apache/lucene/search/vectorhighlight/FieldQuery.java
+++ b/lucene/contrib/highlighter/src/java/org/apache/lucene/search/vectorhighlight/FieldQuery.java
@@ -17,11 +17,11 @@ package org.apache.lucene.search.vectorhighlight;
  */
 
 import java.io.IOException;
-import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -60,7 +60,7 @@ public class FieldQuery {
 
   FieldQuery( Query query, IndexReader reader, boolean phraseHighlight, boolean fieldMatch ) throws IOException {
     this.fieldMatch = fieldMatch;
-    List<Query> flatQueries = new ArrayList<Query>();
+    Set<Query> flatQueries = new LinkedHashSet<Query>();
     flatten( query, reader, flatQueries );
     saveTerms( flatQueries, reader );
     Collection<Query> expandQueries = expand( flatQueries );
@@ -133,7 +133,7 @@ public class FieldQuery {
    *      => expandQueries={a,"b c","c d","b c d"}
    */
   Collection<Query> expand( Collection<Query> flatQueries ){
-    List<Query> expandQueries = new ArrayList<Query>();
+    Set<Query> expandQueries = new LinkedHashSet<Query>();
     for( Iterator<Query> i = flatQueries.iterator(); i.hasNext(); ){
       Query query = i.next();
       i.remove();