diff --git a/src/Application.cpp b/src/Application.cpp
index 4a44115d94..37ca4f3952 100644
--- a/src/Application.cpp
+++ b/src/Application.cpp
@@ -12,8 +12,10 @@
 #include "BitcoinUtil.h"
 #include "key.h"
 #include "utils.h"
+#include "TaggedCache.h"
 
-Application* theApp=NULL;
+
+Application* theApp = NULL;
 
 DatabaseCon::DatabaseCon(const std::string& name, const char *initStrings[], int initCount)
 {
@@ -32,11 +34,12 @@ DatabaseCon::~DatabaseCon()
 
 Application::Application() :
 	mUNL(mIOService),
-	mNetOps(mIOService, &mMasterLedger),
+	mNetOps(mIOService, &mMasterLedger), mNodeCache(16384, 600),
 	mTxnDB(NULL), mLedgerDB(NULL), mWalletDB(NULL), mHashNodeDB(NULL), mNetNodeDB(NULL),
 	mConnectionPool(mIOService), mPeerDoor(NULL), mRPCDoor(NULL)
 {
 	RAND_bytes(mNonce256.begin(), mNonce256.size());
+	RAND_bytes(reinterpret_cast<unsigned char *>(&mNonceST), sizeof(mNonceST));
 }
 
 extern const char *TxnDBInit[], *LedgerDBInit[], *WalletDBInit[], *HashNodeDBInit[], *NetNodeDBInit[];
diff --git a/src/Application.h b/src/Application.h
index 96e58bdeef..55d405c66d 100644
--- a/src/Application.h
+++ b/src/Application.h
@@ -1,6 +1,8 @@
 #ifndef __APPLICATION__
 #define __APPLICATION__
 
+#include <boost/asio.hpp>
+
 #include "LedgerMaster.h"
 #include "UniqueNodeList.h"
 #include "ConnectionPool.h"
@@ -10,12 +12,13 @@
 #include "Wallet.h"
 #include "Peer.h"
 #include "NetworkOPs.h"
+#include "TaggedCache.h"
 #include "../database/database.h"
 
-#include <boost/asio.hpp>
 
 class RPCDoor;
 class PeerDoor;
+typedef TaggedCache< uint256, std::vector<unsigned char> > NodeCache;
 
 class DatabaseCon
 {
@@ -40,6 +43,7 @@ class Application
 	LedgerAcquireMaster		mMasterLedgerAcquire;
 	TransactionMaster		mMasterTransaction;
 	NetworkOPs				mNetOps;
+	NodeCache				mNodeCache;
 
 	DatabaseCon* mTxnDB, *mLedgerDB, *mWalletDB, *mHashNodeDB, *mNetNodeDB;
 
@@ -48,6 +52,7 @@ class Application
 	RPCDoor*				mRPCDoor;
 
 	uint256					mNonce256;
+	std::size_t				mNonceST;
 
 	std::map<std::string, Peer::pointer> mPeerMap;
 	boost::recursive_mutex	mPeerMapLock;
@@ -56,26 +61,28 @@ public:
 	Application();
 	~Application();
 
-	ConnectionPool& getConnectionPool() { return mConnectionPool; }
+	ConnectionPool& getConnectionPool()				{ return mConnectionPool; }
 
-	UniqueNodeList& getUNL() { return mUNL; }
+	UniqueNodeList& getUNL()						{ return mUNL; }
 
-	Wallet& getWallet() { return mWallet ; }
-	NetworkOPs& getOPs() { return mNetOps; }
+	Wallet& getWallet()								{ return mWallet ; }
+	NetworkOPs& getOPs()							{ return mNetOps; }
 
-	boost::asio::io_service& getIOService() { return mIOService; }
+	boost::asio::io_service& getIOService()			{ return mIOService; }
 
-	LedgerMaster& getMasterLedger() { return mMasterLedger; }
-	LedgerAcquireMaster& getMasterLedgerAcquire() { return mMasterLedgerAcquire; }
-	TransactionMaster& getMasterTransaction() { return mMasterTransaction; }
+	LedgerMaster& getMasterLedger()					{ return mMasterLedger; }
+	LedgerAcquireMaster& getMasterLedgerAcquire()	{ return mMasterLedgerAcquire; }
+	TransactionMaster& getMasterTransaction()		{ return mMasterTransaction; }
+	NodeCache& getNodeCache()						{ return mNodeCache; }
 
-	DatabaseCon* getTxnDB() { return mTxnDB; }
-	DatabaseCon* getLedgerDB() { return mLedgerDB; }
-	DatabaseCon* getWalletDB() { return mWalletDB; }
-	DatabaseCon* getHashNodeDB() { return mHashNodeDB; }
-	DatabaseCon* getNetNodeDB() { return mNetNodeDB; }
+	DatabaseCon* getTxnDB()			{ return mTxnDB; }
+	DatabaseCon* getLedgerDB()		{ return mLedgerDB; }
+	DatabaseCon* getWalletDB()		{ return mWalletDB; }
+	DatabaseCon* getHashNodeDB()	{ return mHashNodeDB; }
+	DatabaseCon* getNetNodeDB() 	{ return mNetNodeDB; }
 
-	uint256 getNonce256() { return mNonce256; }
+	uint256 getNonce256()			{ return mNonce256; }
+	std::size_t getNonceST()		{ return mNonceST; }
 
 	void run();
 	void stop();
diff --git a/src/LedgerAcquire.cpp b/src/LedgerAcquire.cpp
index 34bd631e29..1a71d79bc1 100644
--- a/src/LedgerAcquire.cpp
+++ b/src/LedgerAcquire.cpp
@@ -67,7 +67,7 @@ void PeerSet::TimerEntry(boost::weak_ptr<PeerSet> wptr, const boost::system::err
 }
 
 LedgerAcquire::LedgerAcquire(const uint256& hash) : PeerSet(hash, LEDGER_ACQUIRE_TIMEOUT), 
-	mHaveBase(false), mHaveState(false), mHaveTransactions(false)
+	mFilter(&theApp->getNodeCache()), mHaveBase(false), mHaveState(false), mHaveTransactions(false)
 {
 #ifdef DEBUG
 	std::cerr << "Acquiring ledger " << mHash.GetHex() << std::endl;
@@ -152,7 +152,7 @@ void LedgerAcquire::trigger(Peer::pointer peer)
 		{
 			std::vector<SHAMapNode> nodeIDs;
 			std::vector<uint256> nodeHashes;
-			mLedger->peekTransactionMap()->getMissingNodes(nodeIDs, nodeHashes, 128);
+			mLedger->peekTransactionMap()->getMissingNodes(nodeIDs, nodeHashes, 128, &mFilter);
 			if (nodeIDs.empty())
 			{
 				if (!mLedger->peekTransactionMap()->isValid()) mFailed = true;
@@ -204,7 +204,7 @@ void LedgerAcquire::trigger(Peer::pointer peer)
 		{
 			std::vector<SHAMapNode> nodeIDs;
 			std::vector<uint256> nodeHashes;
-			mLedger->peekAccountStateMap()->getMissingNodes(nodeIDs, nodeHashes, 128);
+			mLedger->peekAccountStateMap()->getMissingNodes(nodeIDs, nodeHashes, 128, &mFilter);
 			if (nodeIDs.empty())
 			{
  				if (!mLedger->peekAccountStateMap()->isValid()) mFailed = true;
@@ -303,7 +303,7 @@ bool LedgerAcquire::takeTxNode(const std::list<SHAMapNode>& nodeIDs,
 			if (!mLedger->peekTransactionMap()->addRootNode(mLedger->getTransHash(), *nodeDatait))
 				return false;
 		}
-		else if (!mLedger->peekTransactionMap()->addKnownNode(*nodeIDit, *nodeDatait))
+		else if (!mLedger->peekTransactionMap()->addKnownNode(*nodeIDit, *nodeDatait, &mFilter))
 			return false;
 		++nodeIDit;
 		++nodeDatait;
@@ -333,7 +333,7 @@ bool LedgerAcquire::takeAsNode(const std::list<SHAMapNode>& nodeIDs,
 			if (!mLedger->peekAccountStateMap()->addRootNode(mLedger->getAccountHash(), *nodeDatait))
 				return false;
 		}
-		else if (!mLedger->peekAccountStateMap()->addKnownNode(*nodeIDit, *nodeDatait))
+		else if (!mLedger->peekAccountStateMap()->addKnownNode(*nodeIDit, *nodeDatait, &mFilter))
 			return false;
 		++nodeIDit;
 		++nodeDatait;
diff --git a/src/LedgerAcquire.h b/src/LedgerAcquire.h
index 7e92d024f2..f06c4dbabf 100644
--- a/src/LedgerAcquire.h
+++ b/src/LedgerAcquire.h
@@ -13,6 +13,7 @@
 
 #include "Ledger.h"
 #include "Peer.h"
+#include "TaggedCache.h"
 #include "../obj/src/newcoin.pb.h"
 
 class PeerSet
@@ -53,6 +54,31 @@ private:
 	static void TimerEntry(boost::weak_ptr<PeerSet>, const boost::system::error_code& result);
 };
 
+typedef TaggedCache< uint256, std::vector<unsigned char> > NodeCache;
+typedef std::vector<unsigned char> VUC;
+
+class THSyncFilter : public SHAMapSyncFilter
+{
+protected:
+	NodeCache* mCache;
+
+public:
+	THSyncFilter(NodeCache* cache) : mCache(cache) { ; }
+	virtual void gotNode(const SHAMapNode& id, const uint256& nodeHash,
+		const std::vector<unsigned char>& nodeData, bool)
+	{
+		boost::shared_ptr<VUC> ptr = boost::make_shared<VUC>(nodeData);
+		mCache->canonicalize(nodeHash, ptr);
+	}
+	virtual bool haveNode(const SHAMapNode& id, const uint256& nodeHash, std::vector<unsigned char>& nodeData)
+	{
+		boost::shared_ptr<VUC> entry = mCache->fetch(nodeHash);
+		if (!entry) return false;
+		nodeData = *entry;
+		return true;
+	}
+};
+
 class LedgerAcquire : public PeerSet, public boost::enable_shared_from_this<LedgerAcquire>
 { // A ledger we are trying to acquire
 public:
@@ -60,6 +86,7 @@ public:
 
 protected:
 	Ledger::pointer mLedger;
+	THSyncFilter mFilter;
 	bool mHaveBase, mHaveState, mHaveTransactions;
 
 	std::vector< boost::function<void (LedgerAcquire::pointer)> > mOnComplete;
@@ -106,4 +133,5 @@ public:
 };
 
 #endif
+
 // vim:ts=4
diff --git a/src/LedgerConsensus.cpp b/src/LedgerConsensus.cpp
index e2c95fbe84..d1bae73334 100644
--- a/src/LedgerConsensus.cpp
+++ b/src/LedgerConsensus.cpp
@@ -11,7 +11,8 @@
 
 #define TRUST_NETWORK
 
-TransactionAcquire::TransactionAcquire(const uint256& hash) : PeerSet(hash, 1), mHaveRoot(false)
+TransactionAcquire::TransactionAcquire(const uint256& hash)
+	: PeerSet(hash, 1), mFilter(&theApp->getNodeCache()), mHaveRoot(false)
 {
 	mMap = boost::make_shared<SHAMap>();
 	mMap->setSynching();
@@ -48,7 +49,7 @@ void TransactionAcquire::trigger(Peer::pointer peer)
 		Log(lsTRACE) << "Have root";
 		std::vector<SHAMapNode> nodeIDs;
 		std::vector<uint256> nodeHashes;
-		mMap->getMissingNodes(nodeIDs, nodeHashes, 256);
+		mMap->getMissingNodes(nodeIDs, nodeHashes, 256, &mFilter);
 		if (nodeIDs.empty())
 		{
 			if (mMap->isValid())
@@ -100,7 +101,7 @@ bool TransactionAcquire::takeNodes(const std::list<SHAMapNode>& nodeIDs,
 					return false;
 				else mHaveRoot = true;
 			}
-			else if (!mMap->addKnownNode(*nodeIDit, *nodeDatait))
+			else if (!mMap->addKnownNode(*nodeIDit, *nodeDatait, &mFilter))
 				return false;
 			++nodeIDit;
 			++nodeDatait;
diff --git a/src/LedgerConsensus.h b/src/LedgerConsensus.h
index e2b69e8fd2..3a6aeaecde 100644
--- a/src/LedgerConsensus.h
+++ b/src/LedgerConsensus.h
@@ -21,6 +21,7 @@ public:
 
 protected:
 	SHAMap::pointer		mMap;
+	THSyncFilter		mFilter; // FIXME: Should use transaction master too
 	bool				mHaveRoot;
 
 	void onTimer()						{ trigger(Peer::pointer()); }
@@ -47,7 +48,7 @@ protected:
 	int mYays, mNays;
 	bool mOurPosition;
 	std::vector<unsigned char> transaction;
-	boost::unordered_map<uint256, bool, hash_SMN> mVotes;
+	boost::unordered_map<uint256, bool> mVotes;
 
 public:
 	typedef boost::shared_ptr<LCTransaction> pointer;
@@ -85,17 +86,17 @@ protected:
 	LedgerProposal::pointer mOurPosition;
 
 	// Convergence tracking, trusted peers indexed by hash of public key
-	boost::unordered_map<uint256, LedgerProposal::pointer, hash_SMN> mPeerPositions;
+	boost::unordered_map<uint256, LedgerProposal::pointer> mPeerPositions;
 
 	// Transaction Sets, indexed by hash of transaction tree
-	boost::unordered_map<uint256, SHAMap::pointer, hash_SMN> mComplete;
-	boost::unordered_map<uint256, TransactionAcquire::pointer, hash_SMN> mAcquiring;
+	boost::unordered_map<uint256, SHAMap::pointer> mComplete;
+	boost::unordered_map<uint256, TransactionAcquire::pointer> mAcquiring;
 
 	// Peer sets
-	boost::unordered_map<uint256, std::vector< boost::weak_ptr<Peer> >, hash_SMN> mPeerData;
+	boost::unordered_map<uint256, std::vector< boost::weak_ptr<Peer> > > mPeerData;
 
 	// Disputed transactions
-	boost::unordered_map<uint256, LCTransaction::pointer, hash_SMN> mDisputes;
+	boost::unordered_map<uint256, LCTransaction::pointer> mDisputes;
 
 	// final accept logic
 	static void Saccept(boost::shared_ptr<LedgerConsensus> This, SHAMap::pointer txSet);
diff --git a/src/NetworkOPs.cpp b/src/NetworkOPs.cpp
index 64cdc2ca7d..33838890bd 100644
--- a/src/NetworkOPs.cpp
+++ b/src/NetworkOPs.cpp
@@ -285,7 +285,7 @@ void NetworkOPs::checkState(const boost::system::error_code& result)
 	// Do we have sufficient validations for our last closed ledger? Or do sufficient nodes
 	// agree? And do we have no better ledger available?
 	// If so, we are either tracking or full.
-	boost::unordered_map<uint256, ValidationCount, hash_SMN> ledgers;
+	boost::unordered_map<uint256, ValidationCount> ledgers;
 
 	for (std::vector<Peer::pointer>::iterator it = peerList.begin(), end = peerList.end(); it != end; ++it)
 	{
diff --git a/src/Peer.cpp b/src/Peer.cpp
index 02b975cae5..893db52ab0 100644
--- a/src/Peer.cpp
+++ b/src/Peer.cpp
@@ -726,6 +726,7 @@ void Peer::recvGetLedger(newcoin::TMGetLedger& packet)
 {
 	SHAMap::pointer map;
 	newcoin::TMLedgerData reply;
+	bool fatLeaves = true;
 
 	if (packet.itype() == newcoin::liTS_CANDIDATE)
 	{ // Request is  for a transaction candidate set
@@ -748,6 +749,7 @@ void Peer::recvGetLedger(newcoin::TMGetLedger& packet)
 		reply.set_ledgerseq(0);
 		reply.set_ledgerhash(txHash.begin(), txHash.size());
 		reply.set_type(newcoin::liTS_CANDIDATE);
+		fatLeaves = false; // We'll already have most transactions
 	}
 	else
 	{ // Figure out what ledger they want
@@ -828,7 +830,7 @@ void Peer::recvGetLedger(newcoin::TMGetLedger& packet)
 		}
 		std::vector<SHAMapNode> nodeIDs;
 		std::list< std::vector<unsigned char> > rawNodes;
-		if(map->getNodeFat(mn, nodeIDs, rawNodes))
+		if(map->getNodeFat(mn, nodeIDs, rawNodes, fatLeaves))
 		{
 			std::vector<SHAMapNode>::iterator nodeIDIterator;
 			std::list< std::vector<unsigned char> >::iterator rawNodeIterator;
diff --git a/src/SHAMap.cpp b/src/SHAMap.cpp
index 31ef55c436..c84eec80e0 100644
--- a/src/SHAMap.cpp
+++ b/src/SHAMap.cpp
@@ -15,17 +15,17 @@
 #include "SHAMap.h"
 #include "Application.h"
 
-std::size_t hash_SMN::operator() (const SHAMapNode& mn) const
+std::size_t hash_value(const SHAMapNode& mn)
 {
-	return mn.getDepth()
-		^ *reinterpret_cast<const std::size_t *>(mn.getNodeID().begin())
-		^ *reinterpret_cast<const std::size_t *>(theApp->getNonce256().begin());
+	std::size_t seed = theApp->getNonceST();
+	boost::hash_combine(seed, mn.getDepth());
+	return mn.getNodeID().hash_combine(seed);
 }
 
-std::size_t hash_SMN::operator() (const uint256& u) const
+std::size_t hash_value(const uint256& u)
 {
-	return *reinterpret_cast<const std::size_t *>(u.begin())
-		^ *reinterpret_cast<const std::size_t *>(theApp->getNonce256().begin());
+	std::size_t seed = theApp->getNonceST();
+	return u.hash_combine(seed);
 }
 
 SHAMap::SHAMap(uint32 seq) : mSeq(seq), mState(Modifying)
@@ -671,7 +671,7 @@ void SHAMap::dump(bool hash)
 
 	std::cerr << " MAP Contains" << std::endl;
 	boost::recursive_mutex::scoped_lock sl(mLock);
-	for(boost::unordered_map<SHAMapNode, SHAMapTreeNode::pointer, hash_SMN>::iterator it = mTNByID.begin();
+	for(boost::unordered_map<SHAMapNode, SHAMapTreeNode::pointer>::iterator it = mTNByID.begin();
 			it != mTNByID.end(); ++it)
 	{
 		std::cerr << it->second->getString() << std::endl;
diff --git a/src/SHAMap.h b/src/SHAMap.h
index d5c79586d6..b9090c963d 100644
--- a/src/SHAMap.h
+++ b/src/SHAMap.h
@@ -76,14 +76,8 @@ public:
 	SHAMapNode(const void *ptr, int len);
 };
 
-class hash_SMN
-{
-
-public:
-	std::size_t operator() (const SHAMapNode& mn) const;
-
-	std::size_t operator() (const uint256& u) const;
-};
+extern std::size_t hash_value(const SHAMapNode& mn);
+extern std::size_t hash_value(const uint256& u);
 
 class SHAMapItem
 { // an item stored in a SHAMap
@@ -225,6 +219,18 @@ enum SHAMapState
 	Invalid = 4,		// Map is known not to be valid (usually synching a corrupt ledger)
 };
 
+class SHAMapSyncFilter
+{
+public:
+	SHAMapSyncFilter()				{ ; }
+	virtual ~SHAMapSyncFilter()		{ ; }
+	virtual void gotNode(const SHAMapNode& id, const uint256& nodeHash,
+		const std::vector<unsigned char>& nodeData, bool isLeaf)
+	{ ; }
+	virtual bool haveNode(const SHAMapNode& id, const uint256& nodeHash, std::vector<unsigned char>& nodeData)
+	{ return false; }
+};
+
 class SHAMap
 {
 public:
@@ -234,7 +240,7 @@ public:
 private:
 	uint32 mSeq;
 	mutable boost::recursive_mutex mLock;
-	boost::unordered_map<SHAMapNode, SHAMapTreeNode::pointer, hash_SMN> mTNByID;
+	boost::unordered_map<SHAMapNode, SHAMapTreeNode::pointer> mTNByID;
 
 	boost::shared_ptr<std::map<SHAMapNode, SHAMapTreeNode::pointer> > mDirtyNodes;
 
@@ -299,12 +305,14 @@ public:
 	SHAMapItem::pointer peekPrevItem(const uint256&);
 
 	// comparison/sync functions
-	void getMissingNodes(std::vector<SHAMapNode>& nodeIDs, std::vector<uint256>& hashes, int max);
+	void getMissingNodes(std::vector<SHAMapNode>& nodeIDs, std::vector<uint256>& hashes, int max,
+		SHAMapSyncFilter* filter);
 	bool getNodeFat(const SHAMapNode& node, std::vector<SHAMapNode>& nodeIDs,
-	 std::list<std::vector<unsigned char> >& rawNode);
+	 std::list<std::vector<unsigned char> >& rawNode, bool fatLeaves);
 	bool addRootNode(const uint256& hash, const std::vector<unsigned char>& rootNode);
 	bool addRootNode(const std::vector<unsigned char>& rootNode);
-	bool addKnownNode(const SHAMapNode& nodeID, const std::vector<unsigned char>& rawNode);
+	bool addKnownNode(const SHAMapNode& nodeID, const std::vector<unsigned char>& rawNode,
+		SHAMapSyncFilter* filter);
 
 	// status functions
 	void setImmutable(void)		{ assert(mState != Invalid); mState = Immutable; }
diff --git a/src/SHAMapSync.cpp b/src/SHAMapSync.cpp
index edc59f15c5..d0af0c44d4 100644
--- a/src/SHAMapSync.cpp
+++ b/src/SHAMapSync.cpp
@@ -11,19 +11,20 @@
 
 #include "Log.h"
 
-void SHAMap::getMissingNodes(std::vector<SHAMapNode>& nodeIDs, std::vector<uint256>& hashes, int max)
+void SHAMap::getMissingNodes(std::vector<SHAMapNode>& nodeIDs, std::vector<uint256>& hashes, int max,
+	SHAMapSyncFilter* filter)
 {
 	boost::recursive_mutex::scoped_lock sl(mLock);
 
 	assert(root->isValid());
 	
-	if(root->isFullBelow())
+	if (root->isFullBelow())
 	{
 		clearSynching();
 		return;
 	}
 
-	if(!root->isInner())
+	if (!root->isInner())
 	{
 		Log(lsWARNING) << "synching empty tree";
 		return;
@@ -43,7 +44,27 @@ void SHAMap::getMissingNodes(std::vector<SHAMapNode>& nodeIDs, std::vector<uint2
 			int branch = (base + ii) % 16;
 			if (!node->isEmptyBranch(branch))
 			{
-				SHAMapTreeNode::pointer d = getNode(node->getChildNodeID(branch), node->getChildHash(branch), false);
+				SHAMapNode childID = node->getChildNodeID(branch);
+				const uint256& childHash = node->getChildHash(branch);
+				SHAMapTreeNode::pointer d = getNode(childID, childHash, false);
+				if ((!d) && (filter != NULL))
+				{
+					std::vector<unsigned char> nodeData;
+					if (filter->haveNode(childID, childHash, nodeData))
+					{
+						d = boost::make_shared<SHAMapTreeNode>(childID, nodeData, mSeq);
+						if (childHash != d->getNodeHash())
+						{
+							Log(lsERROR) << "Wrong hash from cached object";
+							d = SHAMapTreeNode::pointer();
+						}
+						else
+						{
+							Log(lsTRACE) << "Got sync node from cache";
+							mTNByID[*d] = d;
+						}
+					}
+				}
 				if (!d)
 				{
 					nodeIDs.push_back(node->getChildNodeID(branch));
@@ -58,14 +79,14 @@ void SHAMap::getMissingNodes(std::vector<SHAMapNode>& nodeIDs, std::vector<uint2
 }
 
 bool SHAMap::getNodeFat(const SHAMapNode& wanted, std::vector<SHAMapNode>& nodeIDs,
-	std::list<std::vector<unsigned char> >& rawNodes)
+	std::list<std::vector<unsigned char> >& rawNodes, bool fatLeaves)
 { // Gets a node and some of its children
 	boost::recursive_mutex::scoped_lock sl(mLock);
 
 	SHAMapTreeNode::pointer node = getNode(wanted);
 	if (!node)
 	{
-		assert(false); // Remove for release, this can happen if we get a bogus request
+		assert(false); // FIXME Remove for release, this can happen if we get a bogus request
 		return false;
 	}
 
@@ -82,7 +103,7 @@ bool SHAMap::getNodeFat(const SHAMapNode& wanted, std::vector<SHAMapNode>& nodeI
 		{
 			SHAMapTreeNode::pointer nextNode = getNode(node->getChildNodeID(i), node->getChildHash(i), false);
 			assert(nextNode);
-			if(nextNode)
+			if (nextNode && (fatLeaves || !nextNode->isLeaf()))
 			{
 				nodeIDs.push_back(*nextNode);
 				Serializer s;
@@ -153,7 +174,8 @@ bool SHAMap::addRootNode(const uint256& hash, const std::vector<unsigned char>&
 	return true;
 }
 
-bool SHAMap::addKnownNode(const SHAMapNode& node, const std::vector<unsigned char>& rawNode)
+bool SHAMap::addKnownNode(const SHAMapNode& node, const std::vector<unsigned char>& rawNode,
+	SHAMapSyncFilter* filter)
 { // return value: true=okay, false=error
 	assert(!node.isRoot());
 	if (!isSynching()) return false;
@@ -199,6 +221,8 @@ bool SHAMap::addKnownNode(const SHAMapNode& node, const std::vector<unsigned cha
 	if (hash != newNode->getNodeHash()) // these aren't the droids we're looking for
 		return false;
 
+	if (filter) filter->gotNode(node, hash, rawNode, newNode->isLeaf());
+
 	mTNByID[*newNode] = newNode;
 	if (!newNode->isLeaf())
 		return true; // only a leaf can fill a branch
@@ -209,7 +233,7 @@ bool SHAMap::addKnownNode(const SHAMapNode& node, const std::vector<unsigned cha
 		iNode = stack.top();
 		stack.pop();
 		assert(iNode->isInner());
-		for(int i = 0; i < 16; ++i)
+		for (int i = 0; i < 16; ++i)
 			if (!iNode->isEmptyBranch(i))
 			{
 				SHAMapTreeNode::pointer nextNode = getNode(iNode->getChildNodeID(i), iNode->getChildHash(i), false);
@@ -234,7 +258,7 @@ bool SHAMap::deepCompare(SHAMap& other)
 		stack.pop();
 
 		SHAMapTreeNode::pointer otherNode;
-		if(node->isRoot()) otherNode = other.root;
+		if (node->isRoot()) otherNode = other.root;
 		else otherNode = other.getNode(*node, node->getNodeHash(), false);
 
 		if (!otherNode)
@@ -262,11 +286,11 @@ bool SHAMap::deepCompare(SHAMap& other)
 		{
 			if (!otherNode->isInner())
 				return false;
-			for(int i=0; i<16; i++)
+			for (int i = 0; i < 16; ++i)
 			{
-				if(node->isEmptyBranch(i))
+				if (node->isEmptyBranch(i))
 				{
-					if(!otherNode->isEmptyBranch(i)) return false;
+					if (!otherNode->isEmptyBranch(i)) return false;
 				}
 				else
 				{
@@ -290,9 +314,9 @@ bool SHAMap::deepCompare(SHAMap& other)
 
 static SHAMapItem::pointer makeRandomAS()
 {
-		Serializer s;
-		for(int d = 0; d < 3; ++d) s.add32(rand());
-		return boost::make_shared<SHAMapItem>(s.getRIPEMD160().to256(), s.peekData());
+	Serializer s;
+	for (int d = 0; d < 3; ++d) s.add32(rand());
+	return boost::make_shared<SHAMapItem>(s.getRIPEMD160().to256(), s.peekData());
 }
 
 static bool confuseMap(SHAMap &map, int count)
@@ -362,32 +386,31 @@ BOOST_AUTO_TEST_CASE( SHAMapSync_test )
 
 	SHAMap source, destination;
 
-
 	// add random data to the source map
 	int items = 10000;
 	for (int i = 0; i < items; ++i)
 		source.addItem(*makeRandomAS(), false);
 
 	Log(lsTRACE) << "Adding items, then removing them";
-	if(!confuseMap(source, 500)) BOOST_FAIL("ConfuseMap");
+	if (!confuseMap(source, 500)) BOOST_FAIL("ConfuseMap");
 
 	source.setImmutable();
 
 	Log(lsTRACE) << "SOURCE COMPLETE, SYNCHING";
 
 	std::vector<SHAMapNode> nodeIDs, gotNodeIDs;
-	std::list<std::vector<unsigned char> > gotNodes;
+	std::list< std::vector<unsigned char> > gotNodes;
 	std::vector<uint256> hashes;
 
 	std::vector<SHAMapNode>::iterator nodeIDIterator;
-	std::list<std::vector<unsigned char> >::iterator rawNodeIterator;
+	std::list< std::vector<unsigned char> >::iterator rawNodeIterator;
 
 	int passes = 0;
 	int nodes = 0;
 
 	destination.setSynching();
 
-	if (!source.getNodeFat(SHAMapNode(), nodeIDs, gotNodes))
+	if (!source.getNodeFat(SHAMapNode(), nodeIDs, gotNodes, (rand() % 2) == 0))
 	{
 		Log(lsFATAL) << "GetNodeFat(root) fails";
 		BOOST_FAIL("GetNodeFat");
@@ -416,14 +439,14 @@ BOOST_AUTO_TEST_CASE( SHAMapSync_test )
 		hashes.clear();
 
 		// get the list of nodes we know we need
-		destination.getMissingNodes(nodeIDs, hashes, 2048);
-		if(nodeIDs.empty()) break;
+		destination.getMissingNodes(nodeIDs, hashes, 2048, NULL);
+		if (nodeIDs.empty()) break;
 
 		Log(lsINFO) << nodeIDs.size() << " needed nodes";
 		
 		// get as many nodes as possible based on this information
 		for (nodeIDIterator = nodeIDs.begin(); nodeIDIterator != nodeIDs.end(); ++nodeIDIterator)
-			if (!source.getNodeFat(*nodeIDIterator, gotNodeIDs, gotNodes))
+			if (!source.getNodeFat(*nodeIDIterator, gotNodeIDs, gotNodes, (rand() % 2) == 0))
 			{
 				Log(lsFATAL) << "GetNodeFat fails";
 				BOOST_FAIL("GetNodeFat");
@@ -446,7 +469,7 @@ BOOST_AUTO_TEST_CASE( SHAMapSync_test )
 #ifdef SMS_DEBUG
 			bytes += rawNodeIterator->size();
 #endif
-			if (!destination.addKnownNode(*nodeIDIterator, *rawNodeIterator))
+			if (!destination.addKnownNode(*nodeIDIterator, *rawNodeIterator, NULL))
 			{
 				Log(lsTRACE) << "AddKnownNode fails";
 				BOOST_FAIL("AddKnownNode");
diff --git a/src/TaggedCache.h b/src/TaggedCache.h
index f5c501d0a9..6f79e172c5 100644
--- a/src/TaggedCache.h
+++ b/src/TaggedCache.h
@@ -4,6 +4,7 @@
 #include <map>
 
 #include <boost/thread/recursive_mutex.hpp>
+#include <boost/unordered_map.hpp>
 #include <boost/shared_ptr.hpp>
 
 // This class implemented a cache and a map. The cache keeps objects alive
@@ -25,10 +26,10 @@ protected:
 	mutable boost::recursive_mutex mLock;
 
 	int mTargetSize, mTargetAge;
-	std::map<key_type, cache_entry> mCache;		// Hold strong reference to recent objects
+	boost::unordered_map<key_type, cache_entry> mCache;	// Hold strong reference to recent objects
 	time_t mLastSweep;
 
-	std::map<key_type, weak_data_ptr> mMap;		// Track stored objects
+	boost::unordered_map<key_type, weak_data_ptr> mMap;	// Track stored objects
 
 public:
 	TaggedCache(int size, int age) : mTargetSize(size), mTargetAge(age), mLastSweep(time(NULL)) { ; }
@@ -81,7 +82,7 @@ template<typename c_Key, typename c_Data> void TaggedCache<c_Key, c_Data>::sweep
 	time_t target = now - mTargetAge;
 
 	// Pass 1, remove old objects from cache
-	typename std::map<key_type, cache_entry>::iterator cit = mCache.begin();
+	typename boost::unordered_map<key_type, cache_entry>::iterator cit = mCache.begin();
 	while (cit != mCache.end())
 	{
 		if (cit->second->second.first < target)
@@ -90,7 +91,7 @@ template<typename c_Key, typename c_Data> void TaggedCache<c_Key, c_Data>::sweep
 	}
 
 	// Pass 2, remove dead objects from map
-	typename std::map<key_type, weak_data_ptr>::iterator mit = mMap.begin();
+	typename boost::unordered_map<key_type, weak_data_ptr>::iterator mit = mMap.begin();
 	while (mit != mMap.end())
 	{
 		if (mit->second->expired())
@@ -104,7 +105,7 @@ template<typename c_Key, typename c_Data> bool TaggedCache<c_Key, c_Data>::touch
 	boost::recursive_mutex::scoped_lock sl(mLock);
 
 	// Is the object in the map?
-	typename std::map<key_type, weak_data_ptr>::iterator mit = mMap.find(key);
+	typename boost::unordered_map<key_type, weak_data_ptr>::iterator mit = mMap.find(key);
 	if (mit == mMap.end()) return false;
 	if (mit->second->expired())
 	{	// in map, but expired
@@ -113,7 +114,7 @@ template<typename c_Key, typename c_Data> bool TaggedCache<c_Key, c_Data>::touch
 	}
 
 	// Is the object in the cache?
-	typename std::map<key_type, cache_entry>::iterator cit = mCache.find(key);
+	typename boost::unordered_map<key_type, cache_entry>::iterator cit = mCache.find(key);
 	if (cit != mCache.end())
 	{ // in both map and cache
 		cit->second->first = time(NULL);
@@ -129,7 +130,7 @@ template<typename c_Key, typename c_Data> bool TaggedCache<c_Key, c_Data>::del(c
 {	// Remove from cache, map unaffected
 	boost::recursive_mutex::scoped_lock sl(mLock);
 
-	typename std::map<key_type, cache_entry>::iterator cit = mCache.find(key);
+	typename boost::unordered_map<key_type, cache_entry>::iterator cit = mCache.find(key);
 	if (cit == mCache.end()) return false;
 	mCache.erase(cit);
 	return true;	
@@ -141,7 +142,7 @@ bool TaggedCache<c_Key, c_Data>::canonicalize(const key_type& key, boost::shared
 	// Return values: true=we had the data already
 	boost::recursive_mutex::scoped_lock sl(mLock);
 
-	typename std::map<key_type, weak_data_ptr>::iterator mit = mMap.find(key);
+	typename boost::unordered_map<key_type, weak_data_ptr>::iterator mit = mMap.find(key);
 	if (mit == mMap.end())
 	{ // not in map
 		mCache.insert(std::make_pair(key, std::make_pair(time(NULL), data)));
@@ -159,7 +160,7 @@ bool TaggedCache<c_Key, c_Data>::canonicalize(const key_type& key, boost::shared
 	assert(!!data);
 
 	// Valid in map, is it in cache?
-	typename std::map<key_type, cache_entry>::iterator cit = mCache.find(key);
+	typename boost::unordered_map<key_type, cache_entry>::iterator cit = mCache.find(key);
 	if (cit != mCache.end())
 		cit->second.first = time(NULL); // Yes, refesh
 	else // no, add to cache
@@ -174,7 +175,7 @@ boost::shared_ptr<c_Data> TaggedCache<c_Key, c_Data>::fetch(const key_type& key)
 	boost::recursive_mutex::scoped_lock sl(mLock);
 
 	// Is it in the map?
-	typename std::map<key_type, weak_data_ptr>::iterator mit = mMap.find(key);
+	typename boost::unordered_map<key_type, weak_data_ptr>::iterator mit = mMap.find(key);
 	if (mit == mMap.end()) return data_ptr(); // No, we're done
 	if (mit->second.expired())
 	{ // in map, but expired
@@ -185,7 +186,7 @@ boost::shared_ptr<c_Data> TaggedCache<c_Key, c_Data>::fetch(const key_type& key)
 	boost::shared_ptr<c_Data> data = mit->second.lock();
 	
 	// Valid in map, is it in the cache?
-	typename std::map<key_type, cache_entry>::iterator cit = mCache.find(key);
+	typename boost::unordered_map<key_type, cache_entry>::iterator cit = mCache.find(key);
 	if (cit != mCache.end())
 		cit->second.first = time(NULL); // Yes, refresh
 	else // No, add to cache
diff --git a/src/Transaction.cpp b/src/Transaction.cpp
index 303b267a15..72930ef294 100644
--- a/src/Transaction.cpp
+++ b/src/Transaction.cpp
@@ -11,6 +11,7 @@
 #include "BitcoinUtil.h"
 #include "Serializer.h"
 #include "SerializedTransaction.h"
+#include "Log.h"
 
 Transaction::Transaction(const SerializedTransaction::pointer sit, bool bValidate)
 	: mInLedger(0), mStatus(INVALID), mTransaction(sit)
@@ -43,6 +44,7 @@ Transaction::pointer Transaction::sharedTransaction(const std::vector<unsigned c
 	}
 	catch (...)
 	{
+		Log(lsWARNING) << "Exception constructing transaction";
 		return boost::shared_ptr<Transaction>();
 	}
 }
@@ -66,8 +68,8 @@ Transaction::Transaction(
 
 	mTransaction	= boost::make_shared<SerializedTransaction>(ttKind);
 
-	std::cerr << str(boost::format("Transaction: account: %s") % naSourceAccount.humanAccountID()) << std::endl;
-	std::cerr << str(boost::format("Transaction: mAccountFrom: %s") % mAccountFrom.humanAccountID()) << std::endl;
+	Log(lsINFO) << str(boost::format("Transaction: account: %s") % naSourceAccount.humanAccountID());
+	Log(lsINFO) << str(boost::format("Transaction: mAccountFrom: %s") % mAccountFrom.humanAccountID());
 	mTransaction->setSigningPubKey(mFromPubKey);
 	mTransaction->setSourceAccount(mAccountFrom);
 	mTransaction->setSequence(uSeq);
@@ -86,16 +88,12 @@ bool Transaction::sign(const NewcoinAddress& naAccountPrivate)
 
 	if (!naAccountPrivate.isValid())
 	{
-#ifdef DEBUG
-		std::cerr << "No private key for signing" << std::endl;
-#endif
+		Log(lsWARNING) << "No private key for signing";
 		bResult	= false;
 	}
 	else if (!getSTransaction()->sign(naAccountPrivate))
 	{
-#ifdef DEBUG
-		std::cerr << "Failed to make signature" << std::endl;
-#endif
+		Log(lsWARNING) << "Failed to make signature";
 		assert(false);
 		bResult	= false;
 	}
diff --git a/src/TransactionEngine.cpp b/src/TransactionEngine.cpp
index fba4c8ab55..c433eea03f 100644
--- a/src/TransactionEngine.cpp
+++ b/src/TransactionEngine.cpp
@@ -291,6 +291,7 @@ TransactionEngineResult TransactionEngine::applyTransaction(const SerializedTran
 	std::cerr << "applyTransaction>" << std::endl;
 
 	mLedger = mDefaultLedger;
+	assert(mLedger);
 	if (mAlternateLedger && (targetLedger != 0) &&
 		(targetLedger != mLedger->getLedgerSeq()) && (targetLedger == mAlternateLedger->getLedgerSeq()))
 	{
diff --git a/src/uint256.h b/src/uint256.h
index 78b9b169c4..356433e619 100644
--- a/src/uint256.h
+++ b/src/uint256.h
@@ -13,6 +13,8 @@
 #include <cstring>
 #include <cassert>
 
+#include <boost/functional/hash.hpp>
+
 #include "types.h"
 #include "utils.h"
 
@@ -136,6 +138,13 @@ public:
 		return ret;
 	}
 
+	std::size_t hash_combine(std::size_t& seed) const
+	{
+		for (int i = 0; i < WIDTH; ++i)
+			boost::hash_combine(seed, pn[i]);
+		return seed;
+	}
+
 	friend inline int compare(const base_uint& a, const base_uint& b)
 	{
 		const unsigned char* pA		= a.begin();