diff --git a/CHANGES.txt b/CHANGES.txt
index 47872a6470c..85b48117791 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -51,6 +51,7 @@ Release 0.91.0 - Unreleased
                unflushable regions.
    HBASE-3550  FilterList reports false positives (Bill Graham via Andrew
                Purtell)
+   HBASE-3514  Speedup HFile.Writer append
 
   IMPROVEMENTS
    HBASE-3290  Max Compaction Size (Nicolas Spiegelberg via Stack)  
diff --git a/src/main/java/org/apache/hadoop/hbase/io/hfile/HFile.java b/src/main/java/org/apache/hadoop/hbase/io/hfile/HFile.java
index 06f391ce00b..a91d7d9ed92 100644
--- a/src/main/java/org/apache/hadoop/hbase/io/hfile/HFile.java
+++ b/src/main/java/org/apache/hadoop/hbase/io/hfile/HFile.java
@@ -221,9 +221,6 @@ public class HFile {
     // Used to ensure we write in order.
     private final RawComparator<byte []> comparator;
 
-    // A stream made per block written.
-    private DataOutputStream out;
-
     // Number of uncompressed bytes per block.  Reinitialized when we start
     // new block.
     private int blocksize;
@@ -264,9 +261,9 @@ public class HFile {
     // Block cache to optionally fill on write
     private BlockCache blockCache;
 
-    // Additional byte array output stream used to fill block cache
-    private ByteArrayOutputStream baos;
-    private DataOutputStream baosDos;
+    // Byte array output stream made per block written.
+    private ByteArrayOutputStream baos = null;
+    private DataOutputStream baosDos = null;
     private int blockNumber = 0;
 
     /**
@@ -360,7 +357,7 @@ public class HFile {
      * @throws IOException
      */
     private void checkBlockBoundary() throws IOException {
-      if (this.out != null && this.out.size() < blocksize) return;
+      if (baosDos != null && baosDos.size() < blocksize) return;
       finishBlock();
       newBlock();
     }
@@ -370,11 +367,18 @@ public class HFile {
      * @throws IOException
      */
     private void finishBlock() throws IOException {
-      if (this.out == null) return;
+      if (baosDos == null) return;
+
+      // Flush Data Output Stream
+      baosDos.flush();
+
+      // Compress Data and write to output stream
+      DataOutputStream compressStream = getCompressingStream();
+      baos.writeTo(compressStream);
+      int size = releaseCompressingStream(compressStream);
+
       long now = System.currentTimeMillis();
 
-      int size = releaseCompressingStream(this.out);
-      this.out = null;
       blockKeys.add(firstKey);
       blockOffsets.add(Long.valueOf(blockBegin));
       blockDataSizes.add(Integer.valueOf(size));
@@ -384,14 +388,17 @@ public class HFile {
       writeOps++;
 
       if (blockCache != null) {
-        baosDos.flush();
         byte [] bytes = baos.toByteArray();
         ByteBuffer blockToCache = ByteBuffer.wrap(bytes, DATABLOCKMAGIC.length,
             bytes.length - DATABLOCKMAGIC.length);
         String blockName = path.toString() + blockNumber;
         blockCache.cacheBlock(blockName, blockToCache);
-        baosDos.close();
       }
+
+      baosDos.close();
+      baosDos = null;
+      baos = null;
+
       blockNumber++;
     }
 
@@ -402,14 +409,14 @@ public class HFile {
     private void newBlock() throws IOException {
       // This is where the next block begins.
       blockBegin = outputStream.getPos();
-      this.out = getCompressingStream();
-      this.out.write(DATABLOCKMAGIC);
+
       firstKey = null;
-      if (blockCache != null) {
-        this.baos = new ByteArrayOutputStream();
-        this.baosDos = new DataOutputStream(baos);
-        this.baosDos.write(DATABLOCKMAGIC);
-      }
+
+      // to avoid too many calls to realloc(),
+      // pre-allocates the byte stream to the block size + 25%
+      baos = new ByteArrayOutputStream(blocksize + (int)(blocksize * 0.25));
+      baosDos = new DataOutputStream(baos);
+      baosDos.write(DATABLOCKMAGIC);
     }
 
     /*
@@ -467,7 +474,7 @@ public class HFile {
       for (i = 0; i < metaNames.size(); ++i) {
         // stop when the current key is greater than our own
         byte[] cur = metaNames.get(i);
-        if (Bytes.BYTES_RAWCOMPARATOR.compare(cur, 0, cur.length, 
+        if (Bytes.BYTES_RAWCOMPARATOR.compare(cur, 0, cur.length,
             key, 0, key.length) > 0) {
           break;
         }
@@ -563,12 +570,12 @@ public class HFile {
         checkBlockBoundary();
       }
       // Write length of key and value and then actual key and value bytes.
-      this.out.writeInt(klength);
+      this.baosDos.writeInt(klength);
       this.keylength += klength;
-      this.out.writeInt(vlength);
+      this.baosDos.writeInt(vlength);
       this.valuelength += vlength;
-      this.out.write(key, koffset, klength);
-      this.out.write(value, voffset, vlength);
+      this.baosDos.write(key, koffset, klength);
+      this.baosDos.write(value, voffset, vlength);
       // Are we the first key in this block?
       if (this.firstKey == null) {
         // Copy the key.
@@ -579,13 +586,6 @@ public class HFile {
       this.lastKeyOffset = koffset;
       this.lastKeyLength = klength;
       this.entryCount ++;
-      // If we are pre-caching blocks on write, fill byte array stream
-      if (blockCache != null) {
-        this.baosDos.writeInt(klength);
-        this.baosDos.writeInt(vlength);
-        this.baosDos.write(key, koffset, klength);
-        this.baosDos.write(value, voffset, vlength);
-      }
     }
 
     /*