diff --git a/binary/jce/reader.go b/binary/jce/reader.go
index 7d2f0a7e..e1f88fb3 100644
--- a/binary/jce/reader.go
+++ b/binary/jce/reader.go
@@ -1,15 +1,16 @@
 package jce
 
 import (
-	"bytes"
 	goBinary "encoding/binary"
-	"io"
 	"math"
 	"reflect"
+
+	"github.com/Mrs4s/MiraiGo/utils"
 )
 
 type JceReader struct {
-	buf *bytes.Reader
+	buf []byte
+	off int
 }
 
 type HeadData struct {
@@ -18,25 +19,26 @@ type HeadData struct {
 }
 
 func NewJceReader(data []byte) *JceReader {
-	buf := bytes.NewReader(data)
-	return &JceReader{buf: buf}
+	return &JceReader{buf: data}
 }
 
 func (r *JceReader) readHead() (hd HeadData, l int32) {
-	b, _ := r.buf.ReadByte()
+	b := r.buf[r.off]
 	hd.Type = b & 0xF
 	hd.Tag = (int(b) & 0xF0) >> 4
+	l = 1
 	if hd.Tag == 15 {
-		b, _ = r.buf.ReadByte()
+		b = r.buf[r.off+1]
 		hd.Tag = int(b) & 0xFF
-		return hd, 2
+		l = 2
 	}
-	return hd, 1
+	r.off += int(l)
+	return
 }
 
 func (r *JceReader) peakHead() (h HeadData, l int32) {
 	h, l = r.readHead()
-	_, _ = r.buf.Seek(int64(-l), io.SeekCurrent)
+	r.off -= int(l)
 	return
 }
 
@@ -55,7 +57,7 @@ func (r *JceReader) skipField(t byte) {
 	case 3, 5:
 		r.skip(8)
 	case 6:
-		b, _ := r.buf.ReadByte()
+		b := r.readByte()
 		r.skip(int(b))
 	case 7:
 		r.skip(int(r.readInt32()))
@@ -89,33 +91,28 @@ func (r *JceReader) SkipField(c int) {
 	}
 }
 
-func (r *JceReader) readBytes(len int) []byte {
-	if len == 0 {
-		return nil
-	}
-	b := make([]byte, len)
-	_, err := r.buf.Read(b)
-	if err != nil {
-		panic(err)
+func (r *JceReader) readBytes(n int) []byte {
+	if r.off+n > len(r.buf) {
+		panic("readBytes: EOF")
 	}
+	b := make([]byte, n)
+	n = copy(b, r.buf[r.off:])
+	r.off += n
 	return b
 }
 
 func (r *JceReader) readByte() byte {
-	b, err := r.buf.ReadByte()
-	if err != nil {
-		panic(err)
+	if r.off >= len(r.buf) {
+		panic("readByte: EOF")
 	}
+	b := r.buf[r.off]
+	r.off++
 	return b
 }
 
 func (r *JceReader) readUInt16() uint16 {
-	f, _ := r.buf.ReadByte()
-	s, err := r.buf.ReadByte()
-	if err != nil {
-		panic(err)
-	}
-	return uint16((int32(f) << 8) + int32(s))
+	b := r.readBytes(2)
+	return uint16((int32(b[0]) << 8) + int32(b[1]))
 }
 
 func (r *JceReader) readInt32() int32 {
@@ -274,9 +271,9 @@ func (r *JceReader) ReadString(tag int) string {
 	hd, _ := r.readHead()
 	switch hd.Type {
 	case 6:
-		return string(r.readBytes(int(r.readByte())))
+		return utils.B2S(r.readBytes(int(r.readByte())))
 	case 7:
-		return string(r.readBytes(int(r.readInt32())))
+		return utils.B2S(r.readBytes(int(r.readInt32())))
 	default:
 		return ""
 	}
@@ -364,35 +361,60 @@ func (r *JceReader) ReadJceStruct(obj IJceStruct, tag int) {
 
 func (r *JceReader) ReadMap(i interface{}, tag int) {
 	v := reflect.ValueOf(i)
-	if v.Kind() != reflect.Map {
-		return
-	}
-	if !r.skipToTag(tag) {
+	r.readMap(v, tag)
+}
+
+func (r *JceReader) readMap(v reflect.Value, tag int) {
+	if v.Kind() != reflect.Map || !r.skipToTag(tag) {
 		return
 	}
 	t := v.Type()
 
 	kt := t.Key()
-	kv := reflect.New(kt)
-
 	vt := t.Elem()
-	vv := reflect.New(vt)
-
 	r.readHead()
 	s := r.ReadInt32(0)
+
+	// map with string key or string value is very common.
+	// specialize for string
+	if kt.Kind() == reflect.String && vt.Kind() == reflect.String {
+		for i := 0; i < int(s); i++ {
+			kv := reflect.ValueOf(r.ReadString(0))
+			vv := reflect.ValueOf(r.ReadString(1))
+			v.SetMapIndex(kv, vv)
+		}
+		return
+	}
+
+	if kt.Kind() == reflect.String {
+		vv := reflect.New(vt)
+		for i := 0; i < int(s); i++ {
+			kv := reflect.ValueOf(r.ReadString(0))
+			r.readObject(vv, 1)
+			v.SetMapIndex(kv, vv.Elem())
+		}
+		return
+	}
+
+	kv := reflect.New(kt)
+	vv := reflect.New(vt)
 	for i := 0; i < int(s); i++ {
-		r.ReadObject(kv.Interface(), 0)
-		r.ReadObject(vv.Interface(), 1)
+		r.readObject(kv, 0)
+		r.readObject(vv, 1)
 		v.SetMapIndex(kv.Elem(), vv.Elem())
 	}
 }
 
 func (r *JceReader) ReadSlice(i interface{}, tag int) {
-	t := reflect.TypeOf(i)
-	v := reflect.ValueOf(i).Elem()
+	r.readSlice(reflect.ValueOf(i), tag)
+}
+
+func (r *JceReader) readSlice(v reflect.Value, tag int) {
+	t := v.Type()
 	if t.Kind() != reflect.Ptr || t.Elem().Kind() != reflect.Slice {
 		return
 	}
+	v = v.Elem()
 	t = t.Elem()
 	if !r.skipToTag(tag) {
 		return
@@ -404,7 +426,7 @@ func (r *JceReader) ReadSlice(i interface{}, tag int) {
 		t = t.Elem()
 		val := reflect.New(t)
 		for i := 0; i < int(s); i++ {
-			r.ReadObject(val.Interface(), 0)
+			r.readObject(val, 0)
 			sv.Index(i).Set(val.Elem())
 		}
 		v.Set(sv)
@@ -417,43 +439,52 @@ func (r *JceReader) ReadSlice(i interface{}, tag int) {
 }
 
 func (r *JceReader) ReadObject(i interface{}, tag int) {
-	va := reflect.ValueOf(i)
-	if va.Kind() != reflect.Ptr || va.IsNil() {
-		return
-	}
-	if ve := va.Elem(); ve.Kind() == reflect.Map {
-		ve.Set(reflect.MakeMap(ve.Type()))
-		r.ReadMap(ve.Interface(), tag)
-		return
-	}
-	switch o := i.(type) {
-	case *byte:
-		*o = r.ReadByte(tag)
-	case *bool:
-		*o = r.ReadBool(tag)
-	case *int16:
-		*o = r.ReadInt16(tag)
-	case *int:
-		*o = int(r.ReadInt32(tag))
-	case *int32:
-		*o = r.ReadInt32(tag)
-	case *int64:
-		*o = r.ReadInt64(tag)
-	case *float32:
-		*o = r.ReadFloat32(tag)
-	case *float64:
-		*o = r.ReadFloat64(tag)
-	case *string:
-		*o = r.ReadString(tag)
-	case *[]byte:
-		r.ReadSlice(o, tag)
-	case IJceStruct:
-		r.readHead()
-		o.ReadFrom(r)
-		r.skipToStructEnd()
-	}
+	v := reflect.ValueOf(i)
+	r.readObject(v, tag)
 }
 
-func (r *JceReader) ReadAvailable() []byte {
-	return r.readBytes(r.buf.Len())
+func (r *JceReader) readObject(v reflect.Value, tag int) {
+	if v.Kind() != reflect.Ptr || v.IsNil() {
+		return
+	}
+	elemType := v.Type().Elem()
+	if elemType.Kind() == reflect.Map {
+		elem := v.Elem()
+		elem.Set(reflect.MakeMap(elem.Type()))
+		r.readMap(elem, tag)
+		return
+	} else if elemType.Kind() == reflect.Slice && // *[]byte
+		elemType.Elem().Kind() == reflect.Uint8 {
+		elem := v.Elem()
+		elem.SetBytes(r.ReadBytes(tag))
+		return
+	}
+
+	switch elemType.Kind() {
+	case reflect.Uint8, reflect.Int8:
+		*(*uint8)(pointerOf(v)) = r.ReadByte(tag)
+	case reflect.Bool:
+		*(*bool)(pointerOf(v)) = r.ReadBool(tag)
+	case reflect.Uint16, reflect.Int16:
+		*(*int16)(pointerOf(v)) = r.ReadInt16(tag)
+	case reflect.Uint32, reflect.Int32:
+		*(*int32)(pointerOf(v)) = r.ReadInt32(tag)
+	case reflect.Uint64, reflect.Int64:
+		*(*int64)(pointerOf(v)) = r.ReadInt64(tag)
+	case reflect.String:
+		*(*string)(pointerOf(v)) = r.ReadString(tag)
+
+	default:
+		// other cases
+		switch o := v.Interface().(type) {
+		case IJceStruct:
+			r.readHead()
+			o.ReadFrom(r)
+			r.skipToStructEnd()
+		case *float32:
+			*o = r.ReadFloat32(tag)
+		case *float64:
+			*o = r.ReadFloat64(tag)
+		}
+	}
 }