diff --git a/common/buf/buffer.go b/common/buf/buffer.go
index 02448e3..3315f45 100644
--- a/common/buf/buffer.go
+++ b/common/buf/buffer.go
@@ -331,6 +331,10 @@ func (b *Buffer) Len() int {
 }
 
 func (b *Buffer) Cap() int {
+	return b.capacity
+}
+
+func (b *Buffer) RawCap() int {
 	return len(b.data)
 }
 
@@ -338,10 +342,6 @@ func (b *Buffer) Bytes() []byte {
 	return b.data[b.start:b.end]
 }
 
-func (b *Buffer) Slice() []byte {
-	return b.data[:b.capacity]
-}
-
 func (b *Buffer) From(n int) []byte {
 	return b.data[b.start+n : b.end]
 }
diff --git a/common/bufio/copy.go b/common/bufio/copy.go
index 914865a..f8e63cd 100644
--- a/common/bufio/copy.go
+++ b/common/bufio/copy.go
@@ -295,17 +295,16 @@ func WritePacketWithPool(originSource N.PacketReader, destinationConn N.PacketWr
 	var notFirstTime bool
 	for _, packetBuffer := range packetBuffers {
 		buffer := buf.NewPacket()
-		readBufferRaw := buffer.Slice()
-		readBuffer := buf.With(readBufferRaw[:len(readBufferRaw)-rearHeadroom])
-		readBuffer.Resize(frontHeadroom, 0)
-		_, err = readBuffer.Write(packetBuffer.Buffer.Bytes())
+		buffer.Resize(frontHeadroom, 0)
+		buffer.Reserve(rearHeadroom)
+		_, err = buffer.Write(packetBuffer.Buffer.Bytes())
 		packetBuffer.Buffer.Release()
 		if err != nil {
 			buffer.Release()
 			continue
 		}
-		dataLen := readBuffer.Len()
-		buffer.Resize(readBuffer.Start(), dataLen)
+		dataLen := buffer.Len()
+		buffer.OverCap(rearHeadroom)
 		err = destinationConn.WritePacket(buffer, packetBuffer.Destination)
 		if err != nil {
 			buffer.Leak()