Index: lucene/facet/src/java/org/apache/lucene/facet/search/CountingFacetsCollector.java
===================================================================
--- lucene/facet/src/java/org/apache/lucene/facet/search/CountingFacetsCollector.java	(revision 1437012)
+++ lucene/facet/src/java/org/apache/lucene/facet/search/CountingFacetsCollector.java	(working copy)
@@ -6,28 +6,30 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map.Entry;
+import java.util.Map;
 
 import org.apache.lucene.facet.index.categorypolicy.OrdinalPolicy;
 import org.apache.lucene.facet.index.params.CategoryListParams;
 import org.apache.lucene.facet.index.params.FacetIndexingParams;
 import org.apache.lucene.facet.search.params.CountFacetRequest;
-import org.apache.lucene.facet.search.params.FacetRequest;
 import org.apache.lucene.facet.search.params.FacetRequest.SortBy;
 import org.apache.lucene.facet.search.params.FacetRequest.SortOrder;
+import org.apache.lucene.facet.search.params.FacetRequest;
 import org.apache.lucene.facet.search.params.FacetSearchParams;
 import org.apache.lucene.facet.search.results.FacetResult;
 import org.apache.lucene.facet.search.results.FacetResultNode;
 import org.apache.lucene.facet.taxonomy.TaxonomyReader;
 import org.apache.lucene.facet.taxonomy.directory.ParallelTaxonomyArrays;
 import org.apache.lucene.index.AtomicReaderContext;
+import org.apache.lucene.index.DocValues.Source;
 import org.apache.lucene.index.DocValues;
-import org.apache.lucene.index.DocValues.Source;
 import org.apache.lucene.search.Collector;
 import org.apache.lucene.search.Scorer;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.FixedBitSet;
 import org.apache.lucene.util.PriorityQueue;
 import org.apache.lucene.util.encoding.DGapVInt8IntDecoder;
+import org.apache.lucene.util.packed.PackedInts;
 
 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
@@ -89,11 +91,93 @@
   private final int[] counts;
   private final String facetsField;
   private final boolean useDirectSource;
-  private final HashMap<Source,FixedBitSet> matchingDocs = new HashMap<Source,FixedBitSet>();
+  private final HashMap<CachedInts,FixedBitSet> matchingDocs = new HashMap<CachedInts,FixedBitSet>();
   
   private DocValues facetsValues;
   private FixedBitSet bits;
-  
+
+  private static class CachedInts {
+    final PackedInts.Reader docOffset;
+    final PackedInts.Reader values;
+
+    public CachedInts(Source source, int maxDoc) {
+      //System.out.println("build cache maxDoc=" + maxDoc);
+      BytesRef buf = new BytesRef();
+
+      // First pass: just count how many ords we have:
+
+      // nocommit this could require long?:
+      int totOrds = 0;
+      int maxOrd = -1;
+
+      for(int docID=0;docID<maxDoc;docID++) {
+        source.getBytes(docID, buf);
+        if (buf.length > 0) {
+          // this document has facets
+          int upto = buf.offset + buf.length;
+          int ord = 0;
+          int offset = buf.offset;
+          int prev = 0;
+          while (offset < upto) {
+            byte b = buf.bytes[offset++];
+            if (b >= 0) {
+              prev = ord = ((ord << 7) | b) + prev;
+              maxOrd = Math.max(maxOrd, ord);
+              totOrds++;
+              ord = 0;
+            } else {
+              ord = (ord << 7) | (b & 0x7F);
+            }
+          }
+        }
+      }
+
+      // Second pass: encode to packed ints:
+      PackedInts.Mutable docOffset = PackedInts.getMutable(maxDoc+1, PackedInts.bitsRequired(totOrds), PackedInts.DEFAULT);
+      PackedInts.Mutable values = PackedInts.getMutable(totOrds, PackedInts.bitsRequired(maxOrd), PackedInts.DEFAULT);
+      //System.out.println("  docOffset = " + docOffset.ramBytesUsed() + " bytes");
+      //System.out.println("  values = " + values.ramBytesUsed() + " bytes");
+      totOrds = 0;
+      for(int docID=0;docID<maxDoc;docID++) {
+        docOffset.set(docID, totOrds);
+        source.getBytes(docID, buf);
+        if (buf.length > 0) {
+          // this document has facets
+          int upto = buf.offset + buf.length;
+          int ord = 0;
+          int offset = buf.offset;
+          int prev = 0;
+          while (offset < upto) {
+            byte b = buf.bytes[offset++];
+            if (b >= 0) {
+              prev = ord = ((ord << 7) | b) + prev;
+              values.set(totOrds, ord);
+              totOrds++;
+              ord = 0;
+            } else {
+              ord = (ord << 7) | (b & 0x7F);
+            }
+          }
+        }
+      }
+      docOffset.set(maxDoc, totOrds);
+
+      this.docOffset = docOffset;
+      this.values = values;
+    }
+  }
+
+  private static final Map<Source,CachedInts> sourceCache = new HashMap<Source,CachedInts>();
+
+  private static synchronized CachedInts getCachedInts(Source source, int maxDoc) {
+    CachedInts ci = sourceCache.get(source);
+    if (ci == null) {
+      ci = new CachedInts(source, maxDoc);
+      sourceCache.put(source, ci);
+    }
+    return ci;
+  }
+    
   public CountingFacetsCollector(FacetSearchParams fsp, TaxonomyReader taxoReader) {
     this(fsp, taxoReader, new FacetArrays(taxoReader.getSize()), false);
   }
@@ -162,7 +246,7 @@
     if (facetsValues != null) {
       Source facetSource = useDirectSource ? facetsValues.getDirectSource() : facetsValues.getSource();
       bits = new FixedBitSet(context.reader().maxDoc());
-      matchingDocs.put(facetSource, bits);
+      matchingDocs.put(getCachedInts(facetSource, context.reader().maxDoc()), bits);
     }
   }
   
@@ -176,31 +260,20 @@
   }
   
   private void countFacets() {
-    for (Entry<Source,FixedBitSet> entry : matchingDocs.entrySet()) {
-      Source facetsSource = entry.getKey();
+    for (Entry<CachedInts,FixedBitSet> entry : matchingDocs.entrySet()) {
+      PackedInts.Reader docOffset = entry.getKey().docOffset;
+      PackedInts.Reader values = entry.getKey().values;
       FixedBitSet bits = entry.getValue();
       int doc = 0;
       int length = bits.length();
       while (doc < length && (doc = bits.nextSetBit(doc)) != -1) {
-        facetsSource .getBytes(doc, buf);
-        if (buf.length > 0) {
-          // this document has facets
-          int upto = buf.offset + buf.length;
-          int ord = 0;
-          int offset = buf.offset;
-          int prev = 0;
-          while (offset < upto) {
-            byte b = buf.bytes[offset++];
-            if (b >= 0) {
-              prev = ord = ((ord << 7) | b) + prev;
-              counts[ord]++;
-              ord = 0;
-            } else {
-              ord = (ord << 7) | (b & 0x7F);
-            }
-          }
+        int start = (int) docOffset.get(doc);
+        int end = (int) docOffset.get(doc+1);
+        // nocommit use bulk read api:
+        for(int i=start;i<end;i++) {
+          counts[(int) values.get(i)]++;
         }
-        ++doc;
+        doc++;
       }
     }
   }