diff --git a/core/blockchain.go b/core/blockchain.go
index a5f146a2d..1fbcdfc6f 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -357,7 +357,12 @@ func (self *BlockChain) AuxValidator() pow.PoW { return self.pow }
 
 // State returns a new mutable state based on the current HEAD block.
 func (self *BlockChain) State() (*state.StateDB, error) {
-	return state.New(self.CurrentBlock().Root(), self.chainDb)
+	return self.StateAt(self.CurrentBlock().Root())
+}
+
+// StateAt returns a new mutable state based on a particular point in time.
+func (self *BlockChain) StateAt(root common.Hash) (*state.StateDB, error) {
+	return self.stateCache.New(root)
 }
 
 // Reset purges the entire blockchain, restoring it to its genesis state.
diff --git a/core/state/statedb.go b/core/state/statedb.go
index 802f37ba0..5c51e3b59 100644
--- a/core/state/statedb.go
+++ b/core/state/statedb.go
@@ -20,6 +20,7 @@ package state
 import (
 	"fmt"
 	"math/big"
+	"sync"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/vm"
@@ -66,6 +67,8 @@ type StateDB struct {
 	txIndex      int
 	logs         map[common.Hash]vm.Logs
 	logSize      uint
+
+	lock sync.Mutex
 }
 
 // Create a new state from a given trie
@@ -86,32 +89,53 @@ func New(root common.Hash, db ethdb.Database) (*StateDB, error) {
 	}, nil
 }
 
-// Reset clears out all emphemeral state objects from the state db, but keeps
-// the underlying state trie to avoid reloading data for the next operations.
-func (self *StateDB) Reset(root common.Hash) error {
+// New creates a new statedb by reusing any journalled tries to avoid costly
+// disk io.
+func (self *StateDB) New(root common.Hash) (*StateDB, error) {
+	self.lock.Lock()
+	defer self.lock.Unlock()
+
 	tr, err := self.openTrie(root)
 	if err != nil {
-		return err
+		return nil, err
 	}
-	*self = StateDB{
+	return &StateDB{
 		db:                self.db,
 		trie:              tr,
-		pastTries:         self.pastTries,
 		codeSizeCache:     self.codeSizeCache,
 		stateObjects:      make(map[common.Address]*StateObject),
 		stateObjectsDirty: make(map[common.Address]struct{}),
 		refund:            new(big.Int),
 		logs:              make(map[common.Hash]vm.Logs),
+	}, nil
+}
+
+// Reset clears out all emphemeral state objects from the state db, but keeps
+// the underlying state trie to avoid reloading data for the next operations.
+func (self *StateDB) Reset(root common.Hash) error {
+	self.lock.Lock()
+	defer self.lock.Unlock()
+
+	tr, err := self.openTrie(root)
+	if err != nil {
+		return err
 	}
+	self.trie = tr
+	self.stateObjects = make(map[common.Address]*StateObject)
+	self.stateObjectsDirty = make(map[common.Address]struct{})
+	self.refund = new(big.Int)
+	self.thash = common.Hash{}
+	self.bhash = common.Hash{}
+	self.txIndex = 0
+	self.logs = make(map[common.Hash]vm.Logs)
+	self.logSize = 0
+
 	return nil
 }
 
 // openTrie creates a trie. It uses an existing trie if one is available
 // from the journal if available.
 func (self *StateDB) openTrie(root common.Hash) (*trie.SecureTrie, error) {
-	if self.trie != nil && self.trie.Hash() == root {
-		return self.trie, nil
-	}
 	for i := len(self.pastTries) - 1; i >= 0; i-- {
 		if self.pastTries[i].Hash() == root {
 			tr := *self.pastTries[i]
@@ -122,6 +146,9 @@ func (self *StateDB) openTrie(root common.Hash) (*trie.SecureTrie, error) {
 }
 
 func (self *StateDB) pushTrie(t *trie.SecureTrie) {
+	self.lock.Lock()
+	defer self.lock.Unlock()
+
 	if len(self.pastTries) >= maxJournalLength {
 		copy(self.pastTries, self.pastTries[1:])
 		self.pastTries[len(self.pastTries)-1] = t
@@ -381,6 +408,9 @@ func (self *StateDB) CreateAccount(addr common.Address) vm.Account {
 //
 
 func (self *StateDB) Copy() *StateDB {
+	self.lock.Lock()
+	defer self.lock.Unlock()
+
 	// Copy all the basic fields, initialize the memory ones
 	state := &StateDB{
 		db:                self.db,
@@ -406,6 +436,9 @@ func (self *StateDB) Copy() *StateDB {
 }
 
 func (self *StateDB) Set(state *StateDB) {
+	self.lock.Lock()
+	defer self.lock.Unlock()
+
 	self.db = state.db
 	self.trie = state.trie
 	self.pastTries = state.pastTries
diff --git a/eth/api.go b/eth/api.go
index d6c0826ed..c2fdbe99c 100644
--- a/eth/api.go
+++ b/eth/api.go
@@ -293,7 +293,7 @@ func (api *PublicDebugAPI) DumpBlock(number uint64) (state.Dump, error) {
 	if block == nil {
 		return state.Dump{}, fmt.Errorf("block #%d not found", number)
 	}
-	stateDb, err := state.New(block.Root(), api.eth.ChainDb())
+	stateDb, err := api.eth.BlockChain().StateAt(block.Root())
 	if err != nil {
 		return state.Dump{}, err
 	}
@@ -406,7 +406,7 @@ func (api *PrivateDebugAPI) traceBlock(block *types.Block, logConfig *vm.LogConf
 	if err := core.ValidateHeader(api.config, blockchain.AuxValidator(), block.Header(), blockchain.GetHeader(block.ParentHash(), block.NumberU64()-1), true, false); err != nil {
 		return false, structLogger.StructLogs(), err
 	}
-	statedb, err := state.New(blockchain.GetBlock(block.ParentHash(), block.NumberU64()-1).Root(), api.eth.ChainDb())
+	statedb, err := blockchain.StateAt(blockchain.GetBlock(block.ParentHash(), block.NumberU64()-1).Root())
 	if err != nil {
 		return false, structLogger.StructLogs(), err
 	}
@@ -501,7 +501,7 @@ func (api *PrivateDebugAPI) TraceTransaction(ctx context.Context, txHash common.
 	if parent == nil {
 		return nil, fmt.Errorf("block parent %x not found", block.ParentHash())
 	}
-	stateDb, err := state.New(parent.Root(), api.eth.ChainDb())
+	stateDb, err := api.eth.BlockChain().StateAt(parent.Root())
 	if err != nil {
 		return nil, err
 	}
diff --git a/eth/api_backend.go b/eth/api_backend.go
index 4f8f06529..4adeb0aa0 100644
--- a/eth/api_backend.go
+++ b/eth/api_backend.go
@@ -81,7 +81,7 @@ func (b *EthApiBackend) StateAndHeaderByNumber(blockNr rpc.BlockNumber) (ethapi.
 	if header == nil {
 		return nil, nil, nil
 	}
-	stateDb, err := state.New(header.Root, b.eth.chainDb)
+	stateDb, err := b.eth.BlockChain().StateAt(header.Root)
 	return EthApiState{stateDb}, header, err
 }
 
diff --git a/ethdb/database.go b/ethdb/database.go
index f93731cfe..a4a27303a 100644
--- a/ethdb/database.go
+++ b/ethdb/database.go
@@ -28,6 +28,7 @@ import (
 	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/syndtr/goleveldb/leveldb"
 	"github.com/syndtr/goleveldb/leveldb/errors"
+	"github.com/syndtr/goleveldb/leveldb/filter"
 	"github.com/syndtr/goleveldb/leveldb/iterator"
 	"github.com/syndtr/goleveldb/leveldb/opt"
 
@@ -84,6 +85,7 @@ func NewLDBDatabase(file string, cache int, handles int) (*LDBDatabase, error) {
 		OpenFilesCacheCapacity: handles,
 		BlockCacheCapacity:     cache / 2 * opt.MiB,
 		WriteBuffer:            cache / 4 * opt.MiB, // Two of these are used internally
+		Filter:                 filter.NewBloomFilter(10),
 	})
 	if _, corrupted := err.(*errors.ErrCorrupted); corrupted {
 		db, err = leveldb.RecoverFile(file, nil)
diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index 6480085dd..9a97be25f 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -454,6 +454,8 @@ type CallArgs struct {
 }
 
 func (s *PublicBlockChainAPI) doCall(ctx context.Context, args CallArgs, blockNr rpc.BlockNumber) (string, *big.Int, error) {
+	defer func(start time.Time) { glog.V(logger.Debug).Infof("call took %v", time.Since(start)) }(time.Now())
+
 	state, header, err := s.b.StateAndHeaderByNumber(blockNr)
 	if state == nil || err != nil {
 		return "0x", common.Big0, err
diff --git a/miner/worker.go b/miner/worker.go
index 1676036d8..ac1ef5ba3 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -361,7 +361,7 @@ func (self *worker) push(work *Work) {
 
 // makeCurrent creates a new environment for the current cycle.
 func (self *worker) makeCurrent(parent *types.Block, header *types.Header) error {
-	state, err := state.New(parent.Root(), self.eth.ChainDb())
+	state, err := self.chain.StateAt(parent.Root())
 	if err != nil {
 		return err
 	}
diff --git a/trie/secure_trie.go b/trie/secure_trie.go
index efe875bc8..2a8b57214 100644
--- a/trie/secure_trie.go
+++ b/trie/secure_trie.go
@@ -24,6 +24,8 @@ import (
 
 var secureKeyPrefix = []byte("secure-key-")
 
+const secureKeyLength = 11 + 32 // Length of the above prefix + 32byte hash
+
 // SecureTrie wraps a trie with key hashing. In a secure trie, all
 // access operations hash the key using keccak256. This prevents
 // calling code from creating long chains of nodes that
@@ -35,10 +37,11 @@ var secureKeyPrefix = []byte("secure-key-")
 //
 // SecureTrie is not safe for concurrent use.
 type SecureTrie struct {
-	trie        Trie
-	hashKeyBuf  []byte
-	secKeyBuf   [200]byte
-	secKeyCache map[string][]byte
+	trie             Trie
+	hashKeyBuf       [secureKeyLength]byte
+	secKeyBuf        [200]byte
+	secKeyCache      map[string][]byte
+	secKeyCacheOwner *SecureTrie // Pointer to self, replace the key cache on mismatch
 }
 
 // NewSecure creates a trie with an existing root node from db.
@@ -56,8 +59,7 @@ func NewSecure(root common.Hash, db Database) (*SecureTrie, error) {
 		return nil, err
 	}
 	return &SecureTrie{
-		trie:        *trie,
-		secKeyCache: make(map[string][]byte),
+		trie: *trie,
 	}, nil
 }
 
@@ -104,7 +106,7 @@ func (t *SecureTrie) TryUpdate(key, value []byte) error {
 	if err != nil {
 		return err
 	}
-	t.secKeyCache[string(hk)] = common.CopyBytes(key)
+	t.getSecKeyCache()[string(hk)] = common.CopyBytes(key)
 	return nil
 }
 
@@ -119,14 +121,14 @@ func (t *SecureTrie) Delete(key []byte) {
 // If a node was not found in the database, a MissingNodeError is returned.
 func (t *SecureTrie) TryDelete(key []byte) error {
 	hk := t.hashKey(key)
-	delete(t.secKeyCache, string(hk))
+	delete(t.getSecKeyCache(), string(hk))
 	return t.trie.TryDelete(hk)
 }
 
 // GetKey returns the sha3 preimage of a hashed key that was
 // previously used to store a value.
 func (t *SecureTrie) GetKey(shaKey []byte) []byte {
-	if key, ok := t.secKeyCache[string(shaKey)]; ok {
+	if key, ok := t.getSecKeyCache()[string(shaKey)]; ok {
 		return key
 	}
 	key, _ := t.trie.db.Get(t.secKey(shaKey))
@@ -165,7 +167,7 @@ func (t *SecureTrie) NodeIterator() *NodeIterator {
 // the trie's database. Calling code must ensure that the changes made to db are
 // written back to the trie's attached database before using the trie.
 func (t *SecureTrie) CommitTo(db DatabaseWriter) (root common.Hash, err error) {
-	if len(t.secKeyCache) > 0 {
+	if len(t.getSecKeyCache()) > 0 {
 		for hk, key := range t.secKeyCache {
 			if err := db.Put(t.secKey([]byte(hk)), key); err != nil {
 				return common.Hash{}, err
@@ -196,3 +198,14 @@ func (t *SecureTrie) hashKey(key []byte) []byte {
 	returnHasherToPool(h)
 	return buf
 }
+
+// getSecKeyCache returns the current secure key cache, creating a new one if
+// ownership changed (i.e. the current secure trie is a copy of another owning
+// the actual cache).
+func (t *SecureTrie) getSecKeyCache() map[string][]byte {
+	if t != t.secKeyCacheOwner {
+		t.secKeyCacheOwner = t
+		t.secKeyCache = make(map[string][]byte)
+	}
+	return t.secKeyCache
+}
diff --git a/trie/secure_trie_test.go b/trie/secure_trie_test.go
index 0be5b3d15..3171b8c31 100644
--- a/trie/secure_trie_test.go
+++ b/trie/secure_trie_test.go
@@ -18,6 +18,8 @@ package trie
 
 import (
 	"bytes"
+	"runtime"
+	"sync"
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -31,6 +33,37 @@ func newEmptySecure() *SecureTrie {
 	return trie
 }
 
+// makeTestSecureTrie creates a large enough secure trie for testing.
+func makeTestSecureTrie() (ethdb.Database, *SecureTrie, map[string][]byte) {
+	// Create an empty trie
+	db, _ := ethdb.NewMemDatabase()
+	trie, _ := NewSecure(common.Hash{}, db)
+
+	// Fill it with some arbitrary data
+	content := make(map[string][]byte)
+	for i := byte(0); i < 255; i++ {
+		// Map the same data under multiple keys
+		key, val := common.LeftPadBytes([]byte{1, i}, 32), []byte{i}
+		content[string(key)] = val
+		trie.Update(key, val)
+
+		key, val = common.LeftPadBytes([]byte{2, i}, 32), []byte{i}
+		content[string(key)] = val
+		trie.Update(key, val)
+
+		// Add some other data to inflate th trie
+		for j := byte(3); j < 13; j++ {
+			key, val = common.LeftPadBytes([]byte{j, i}, 32), []byte{j, i}
+			content[string(key)] = val
+			trie.Update(key, val)
+		}
+	}
+	trie.Commit()
+
+	// Return the generated trie
+	return db, trie, content
+}
+
 func TestSecureDelete(t *testing.T) {
 	trie := newEmptySecure()
 	vals := []struct{ k, v string }{
@@ -72,3 +105,41 @@ func TestSecureGetKey(t *testing.T) {
 		t.Errorf("GetKey returned %q, want %q", k, key)
 	}
 }
+
+func TestSecureTrieConcurrency(t *testing.T) {
+	// Create an initial trie and copy if for concurrent access
+	_, trie, _ := makeTestSecureTrie()
+
+	threads := runtime.NumCPU()
+	tries := make([]*SecureTrie, threads)
+	for i := 0; i < threads; i++ {
+		cpy := *trie
+		tries[i] = &cpy
+	}
+	// Start a batch of goroutines interactng with the trie
+	pend := new(sync.WaitGroup)
+	pend.Add(threads)
+	for i := 0; i < threads; i++ {
+		go func(index int) {
+			defer pend.Done()
+
+			for j := byte(0); j < 255; j++ {
+				// Map the same data under multiple keys
+				key, val := common.LeftPadBytes([]byte{byte(index), 1, j}, 32), []byte{j}
+				tries[index].Update(key, val)
+
+				key, val = common.LeftPadBytes([]byte{byte(index), 2, j}, 32), []byte{j}
+				tries[index].Update(key, val)
+
+				// Add some other data to inflate the trie
+				for k := byte(3); k < 13; k++ {
+					key, val = common.LeftPadBytes([]byte{byte(index), k, j}, 32), []byte{k, j}
+					tries[index].Update(key, val)
+				}
+			}
+			tries[index].Commit()
+		}(i)
+	}
+	// Wait for all threads to finish
+	pend.Wait()
+}