diff --git a/store/localstore/kv.go b/store/localstore/kv.go
index a733f28c20..6dcb59915a 100644
--- a/store/localstore/kv.go
+++ b/store/localstore/kv.go
@@ -52,7 +52,7 @@ type storeCache struct {
 var (
 	globalID int64
 
-	providerMu            sync.Mutex
+	providerMu            sync.RWMutex
 	globalVersionProvider kv.VersionProvider
 	mc                    storeCache
 
@@ -77,14 +77,6 @@ func IsLocalStore(s kv.Storage) bool {
 	return ok
 }
 
-func lockVersionProvider() {
-	providerMu.Lock()
-}
-
-func unlockVersionProvider() {
-	providerMu.Unlock()
-}
-
 // Open opens or creates a storage with specific format for a local engine Driver.
 func (d Driver) Open(schema string) (kv.Storage, error) {
 	mc.mu.Lock()
@@ -150,19 +142,20 @@ func (s *dbStore) CurrentVersion() (kv.Version, error) {
 
 // Begin transaction
 func (s *dbStore) Begin() (kv.Transaction, error) {
-	lockVersionProvider()
+	providerMu.RLock()
 	beginVer, err := globalVersionProvider.CurrentVersion()
-	unlockVersionProvider()
+	providerMu.RUnlock()
 	if err != nil {
 		return nil, errors.Trace(err)
 	}
 
 	s.mu.Lock()
-	defer s.mu.Unlock()
-
 	if s.closed {
+		s.mu.Unlock()
 		return nil, errors.Trace(ErrDBClosed)
 	}
+	s.mu.Unlock()
+
 	txn := &dbTxn{
 		tid:          beginVer.Ver,
 		valid:        true,
@@ -223,6 +216,8 @@ func (s *dbStore) newBatch() engine.Batch {
 
 // Both lock and unlock are used for simulating scenario of percolator papers.
 func (s *dbStore) tryConditionLockKey(tid uint64, key string) error {
+	metaKey := codec.EncodeBytes(nil, []byte(key))
+
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
@@ -234,7 +229,6 @@ func (s *dbStore) tryConditionLockKey(tid uint64, key string) error {
 		return errors.Trace(kv.ErrLockConflict)
 	}
 
-	metaKey := codec.EncodeBytes(nil, []byte(key))
 	currValue, err := s.db.Get(metaKey)
 	if terror.ErrorEqual(err, kv.ErrNotExist) {
 		s.keysLocked[key] = tid
diff --git a/store/localstore/txn.go b/store/localstore/txn.go
index b84fe74ed4..80e39adba2 100644
--- a/store/localstore/txn.go
+++ b/store/localstore/txn.go
@@ -218,8 +218,8 @@ func (txn *dbTxn) doCommit() error {
 	}
 
 	// disable version provider temporarily
-	lockVersionProvider()
-	defer unlockVersionProvider()
+	providerMu.Lock()
+	defer providerMu.Unlock()
 
 	curVer, err := globalVersionProvider.CurrentVersion()
 	if err != nil {
diff --git a/util/codec/bytes.go b/util/codec/bytes.go
index 11c8bdf12e..8168d82733 100644
--- a/util/codec/bytes.go
+++ b/util/codec/bytes.go
@@ -47,9 +47,12 @@ import (
 // EncodeBytes guarantees the encoded value is in ascending order for comparison,
 // The encoded value is >= SmallestNoneNilValue and < InfiniteValue.
 func EncodeBytes(b []byte, data []byte) []byte {
+	// Allocate more space to avoid unnecessary slice growing
+	bs := make([]byte, len(b), len(b)+len(data)+20)
+	copy(bs, b)
 	if len(data) > 0 && data[0] == 0xFF {
 		// we must escape 0xFF here to guarantee encoded value < InfiniteValue \xFF\xFF.
-		b = append(b, 0xFF, 0x00)
+		bs = append(bs, 0xFF, 0x00)
 		data = data[1:]
 	}
 
@@ -59,12 +62,12 @@ func EncodeBytes(b []byte, data []byte) []byte {
 		if i == -1 {
 			break
 		}
-		b = append(b, data[:i]...)
-		b = append(b, 0x00, 0xFF)
+		bs = append(bs, data[:i]...)
+		bs = append(bs, 0x00, 0xFF)
 		data = data[i+1:]
 	}
-	b = append(b, data...)
-	return append(b, 0x00, 0x01)
+	bs = append(bs, data...)
+	return append(bs, 0x00, 0x01)
 }
 
 // DecodeBytes decodes bytes which is encoded by EncodeBytes before,
@@ -78,7 +81,8 @@ func decodeBytes(b []byte, escapeFirst byte, escape byte, term byte) ([]byte, []
 		return nil, nil, errors.Errorf("insufficient bytes to decode value")
 	}
 
-	var r []byte
+	// Allocate more space to avoid unnecessary slice growing
+	r := make([]byte, 0, len(b)+20)
 
 	if b[0] == escapeFirst {
 		if b[1] != ^escapeFirst {