diff --git a/trie/encoding.go b/trie/encoding.go
index 524807f06..8daf503a3 100644
--- a/trie/encoding.go
+++ b/trie/encoding.go
@@ -18,11 +18,9 @@ package trie
 
 import (
 	"bytes"
-	"encoding/hex"
-	"strings"
 )
 
-func CompactEncode(hexSlice []byte) string {
+func CompactEncode(hexSlice []byte) []byte {
 	terminator := 0
 	if hexSlice[len(hexSlice)-1] == 16 {
 		terminator = 1
@@ -45,10 +43,10 @@ func CompactEncode(hexSlice []byte) string {
 		buff.WriteByte(byte(16*hexSlice[i] + hexSlice[i+1]))
 	}
 
-	return buff.String()
+	return buff.Bytes()
 }
 
-func CompactDecode(str string) []byte {
+func CompactDecode(str []byte) []byte {
 	base := CompactHexDecode(str)
 	base = base[:len(base)-1]
 	if base[0] >= 2 {
@@ -63,30 +61,23 @@ func CompactDecode(str string) []byte {
 	return base
 }
 
-func CompactHexDecode(str string) []byte {
-	base := "0123456789abcdef"
-	var hexSlice []byte
+func CompactHexDecode(str []byte) []byte {
+	var nibbles []byte
 
-	enc := hex.EncodeToString([]byte(str))
-	for _, v := range enc {
-		hexSlice = append(hexSlice, byte(strings.IndexByte(base, byte(v))))
+	for _, b := range str {
+		nibbles = append(nibbles, b/16)
+		nibbles = append(nibbles, b%16)
 	}
-	hexSlice = append(hexSlice, 16)
-
-	return hexSlice
+	nibbles = append(nibbles, 16)
+	return nibbles
 }
 
-func DecodeCompact(key []byte) string {
-	const base = "0123456789abcdef"
-	var str string
-
-	for _, v := range key {
-		if v < 16 {
-			str += string(base[v])
-		}
+// assumes key is odd length
+func DecodeCompact(key []byte) []byte {
+	var res []byte
+	for i := 0; i < len(key)-1; i += 2 {
+		v1, v0 := key[i], key[i+1]
+		res = append(res, v1*16+v0)
 	}
-
-	res, _ := hex.DecodeString(str)
-
-	return string(res)
+	return res
 }
diff --git a/trie/encoding_test.go b/trie/encoding_test.go
index e52c6ba8d..faaa7f583 100644
--- a/trie/encoding_test.go
+++ b/trie/encoding_test.go
@@ -48,28 +48,28 @@ func (s *TrieEncodingSuite) TestCompactEncode(c *checker.C) {
 
 func (s *TrieEncodingSuite) TestCompactHexDecode(c *checker.C) {
 	exp := []byte{7, 6, 6, 5, 7, 2, 6, 2, 16}
-	res := CompactHexDecode("verb")
+	res := CompactHexDecode([]byte("verb"))
 	c.Assert(res, checker.DeepEquals, exp)
 }
 
 func (s *TrieEncodingSuite) TestCompactDecode(c *checker.C) {
 	// odd compact decode
 	exp := []byte{1, 2, 3, 4, 5}
-	res := CompactDecode("\x11\x23\x45")
+	res := CompactDecode([]byte("\x11\x23\x45"))
 	c.Assert(res, checker.DeepEquals, exp)
 
 	// even compact decode
 	exp = []byte{0, 1, 2, 3, 4, 5}
-	res = CompactDecode("\x00\x01\x23\x45")
+	res = CompactDecode([]byte("\x00\x01\x23\x45"))
 	c.Assert(res, checker.DeepEquals, exp)
 
 	// even terminated compact decode
 	exp = []byte{0, 15, 1, 12, 11, 8 /*term*/, 16}
-	res = CompactDecode("\x20\x0f\x1c\xb8")
+	res = CompactDecode([]byte("\x20\x0f\x1c\xb8"))
 	c.Assert(res, checker.DeepEquals, exp)
 
 	// even terminated compact decode
 	exp = []byte{15, 1, 12, 11, 8 /*term*/, 16}
-	res = CompactDecode("\x3f\x1c\xb8")
+	res = CompactDecode([]byte("\x3f\x1c\xb8"))
 	c.Assert(res, checker.DeepEquals, exp)
 }
diff --git a/trie/iterator.go b/trie/iterator.go
index 698e64b34..9c4c7fbe5 100644
--- a/trie/iterator.go
+++ b/trie/iterator.go
@@ -41,7 +41,7 @@ func (self *Iterator) Next() bool {
 		self.Key = make([]byte, 32)
 	}
 
-	key := RemTerm(CompactHexDecode(string(self.Key)))
+	key := RemTerm(CompactHexDecode(self.Key))
 	k := self.next(self.trie.root, key, isIterStart)
 
 	self.Key = []byte(DecodeCompact(k))
diff --git a/trie/shortnode.go b/trie/shortnode.go
index b5fc6d1f9..569d5f109 100644
--- a/trie/shortnode.go
+++ b/trie/shortnode.go
@@ -26,7 +26,7 @@ type ShortNode struct {
 }
 
 func NewShortNode(t *Trie, key []byte, value Node) *ShortNode {
-	return &ShortNode{t, []byte(CompactEncode(key)), value, false}
+	return &ShortNode{t, CompactEncode(key), value, false}
 }
 func (self *ShortNode) Value() Node {
 	self.value = self.trie.trans(self.value)
@@ -49,7 +49,7 @@ func (self *ShortNode) Hash() interface{} {
 }
 
 func (self *ShortNode) Key() []byte {
-	return CompactDecode(string(self.key))
+	return CompactDecode(self.key)
 }
 
 func (self *ShortNode) setDirty(dirty bool) {
diff --git a/trie/trie.go b/trie/trie.go
index e7ee86402..abf48a850 100644
--- a/trie/trie.go
+++ b/trie/trie.go
@@ -69,7 +69,7 @@ func (self *Trie) Iterator() *Iterator {
 
 func (self *Trie) Copy() *Trie {
 	cpy := make([]byte, 32)
-	copy(cpy, self.roothash)
+	copy(cpy, self.roothash) // NOTE: cpy isn't being used anywhere?
 	trie := New(nil, nil)
 	trie.cache = self.cache.Copy()
 	if self.root != nil {
@@ -131,7 +131,7 @@ func (self *Trie) Update(key, value []byte) Node {
 	self.mu.Lock()
 	defer self.mu.Unlock()
 
-	k := CompactHexDecode(string(key))
+	k := CompactHexDecode(key)
 
 	if len(value) != 0 {
 		node := NewValueNode(self, value)
@@ -149,7 +149,7 @@ func (self *Trie) Get(key []byte) []byte {
 	self.mu.Lock()
 	defer self.mu.Unlock()
 
-	k := CompactHexDecode(string(key))
+	k := CompactHexDecode(key)
 
 	n := self.get(self.root, k)
 	if n != nil {
@@ -164,7 +164,7 @@ func (self *Trie) Delete(key []byte) Node {
 	self.mu.Lock()
 	defer self.mu.Unlock()
 
-	k := CompactHexDecode(string(key))
+	k := CompactHexDecode(key)
 	self.root = self.delete(self.root, k)
 
 	return self.root
@@ -336,7 +336,7 @@ func (self *Trie) mknode(value *common.Value) Node {
 	case 2:
 		// A value node may consists of 2 bytes.
 		if value.Get(0).Len() != 0 {
-			key := CompactDecode(string(value.Get(0).Bytes()))
+			key := CompactDecode(value.Get(0).Bytes())
 			if key[len(key)-1] == 16 {
 				return NewShortNode(self, key, NewValueNode(self, value.Get(1).Bytes()))
 			} else {