diff --git a/app/proxyman/mux/mux.go b/app/proxyman/mux/mux.go
index 5470a2937..fb44919a0 100644
--- a/app/proxyman/mux/mux.go
+++ b/app/proxyman/mux/mux.go
@@ -192,25 +192,25 @@ func (m *Client) Dispatch(ctx context.Context, outboundRay ray.OutboundRay) bool
 	return true
 }
 
-func drain(reader io.Reader) error {
+func drain(reader *buf.BufferedReader) error {
 	return buf.Copy(NewStreamReader(reader), buf.Discard)
 }
 
-func (m *Client) handleStatueKeepAlive(meta *FrameMetadata, reader io.Reader) error {
+func (m *Client) handleStatueKeepAlive(meta *FrameMetadata, reader *buf.BufferedReader) error {
 	if meta.Option.Has(OptionData) {
 		return drain(reader)
 	}
 	return nil
 }
 
-func (m *Client) handleStatusNew(meta *FrameMetadata, reader io.Reader) error {
+func (m *Client) handleStatusNew(meta *FrameMetadata, reader *buf.BufferedReader) error {
 	if meta.Option.Has(OptionData) {
 		return drain(reader)
 	}
 	return nil
 }
 
-func (m *Client) handleStatusKeep(meta *FrameMetadata, reader io.Reader) error {
+func (m *Client) handleStatusKeep(meta *FrameMetadata, reader *buf.BufferedReader) error {
 	if !meta.Option.Has(OptionData) {
 		return nil
 	}
@@ -221,7 +221,7 @@ func (m *Client) handleStatusKeep(meta *FrameMetadata, reader io.Reader) error {
 	return drain(reader)
 }
 
-func (m *Client) handleStatusEnd(meta *FrameMetadata, reader io.Reader) error {
+func (m *Client) handleStatusEnd(meta *FrameMetadata, reader *buf.BufferedReader) error {
 	if s, found := m.sessionManager.Get(meta.SessionID); found {
 		s.Close()
 	}
@@ -315,14 +315,14 @@ func handle(ctx context.Context, s *Session, output buf.Writer) {
 	s.Close()
 }
 
-func (w *ServerWorker) handleStatusKeepAlive(meta *FrameMetadata, reader io.Reader) error {
+func (w *ServerWorker) handleStatusKeepAlive(meta *FrameMetadata, reader *buf.BufferedReader) error {
 	if meta.Option.Has(OptionData) {
 		return drain(reader)
 	}
 	return nil
 }
 
-func (w *ServerWorker) handleStatusNew(ctx context.Context, meta *FrameMetadata, reader io.Reader) error {
+func (w *ServerWorker) handleStatusNew(ctx context.Context, meta *FrameMetadata, reader *buf.BufferedReader) error {
 	log.Trace(newError("received request for ", meta.Target))
 	inboundRay, err := w.dispatcher.Dispatch(ctx, meta.Target)
 	if err != nil {
@@ -349,7 +349,7 @@ func (w *ServerWorker) handleStatusNew(ctx context.Context, meta *FrameMetadata,
 	return nil
 }
 
-func (w *ServerWorker) handleStatusKeep(meta *FrameMetadata, reader io.Reader) error {
+func (w *ServerWorker) handleStatusKeep(meta *FrameMetadata, reader *buf.BufferedReader) error {
 	if !meta.Option.Has(OptionData) {
 		return nil
 	}
@@ -359,7 +359,7 @@ func (w *ServerWorker) handleStatusKeep(meta *FrameMetadata, reader io.Reader) e
 	return drain(reader)
 }
 
-func (w *ServerWorker) handleStatusEnd(meta *FrameMetadata, reader io.Reader) error {
+func (w *ServerWorker) handleStatusEnd(meta *FrameMetadata, reader *buf.BufferedReader) error {
 	if s, found := w.sessionManager.Get(meta.SessionID); found {
 		s.Close()
 	}
@@ -369,7 +369,7 @@ func (w *ServerWorker) handleStatusEnd(meta *FrameMetadata, reader io.Reader) er
 	return nil
 }
 
-func (w *ServerWorker) handleFrame(ctx context.Context, reader io.Reader) error {
+func (w *ServerWorker) handleFrame(ctx context.Context, reader *buf.BufferedReader) error {
 	meta, err := ReadMetadata(reader)
 	if err != nil {
 		return newError("failed to read metadata").Base(err)
diff --git a/app/proxyman/mux/reader.go b/app/proxyman/mux/reader.go
index 80192dc9d..df13ed2bf 100644
--- a/app/proxyman/mux/reader.go
+++ b/app/proxyman/mux/reader.go
@@ -67,12 +67,12 @@ func (r *PacketReader) ReadMultiBuffer() (buf.MultiBuffer, error) {
 
 // StreamReader reads Mux frame as a stream.
 type StreamReader struct {
-	reader   io.Reader
+	reader   *buf.BufferedReader
 	leftOver int
 }
 
 // NewStreamReader creates a new StreamReader.
-func NewStreamReader(reader io.Reader) *StreamReader {
+func NewStreamReader(reader *buf.BufferedReader) *StreamReader {
 	return &StreamReader{
 		reader:   reader,
 		leftOver: -1,
@@ -94,25 +94,7 @@ func (r *StreamReader) ReadMultiBuffer() (buf.MultiBuffer, error) {
 		r.leftOver = int(size)
 	}
 
-	mb := buf.NewMultiBufferCap(32)
-	for r.leftOver > 0 {
-		readLen := buf.Size
-		if r.leftOver < readLen {
-			readLen = r.leftOver
-		}
-		b := buf.New()
-		if err := b.AppendSupplier(func(bb []byte) (int, error) {
-			return r.reader.Read(bb[:readLen])
-		}); err != nil {
-			b.Release()
-			mb.Release()
-			return nil, err
-		}
-		r.leftOver -= b.Len()
-		mb.Append(b)
-		if b.Len() < readLen {
-			break
-		}
-	}
-	return mb, nil
+	mb, err := r.reader.ReadAtMost(r.leftOver)
+	r.leftOver -= mb.Len()
+	return mb, err
 }
diff --git a/app/proxyman/mux/session.go b/app/proxyman/mux/session.go
index 8704a0d43..66e1b7290 100644
--- a/app/proxyman/mux/session.go
+++ b/app/proxyman/mux/session.go
@@ -1,7 +1,6 @@
 package mux
 
 import (
-	"io"
 	"sync"
 
 	"v2ray.com/core/common/buf"
@@ -139,7 +138,7 @@ func (s *Session) Close() {
 }
 
 // NewReader creates a buf.Reader based on the transfer type of this Session.
-func (s *Session) NewReader(reader io.Reader) buf.Reader {
+func (s *Session) NewReader(reader *buf.BufferedReader) buf.Reader {
 	if s.transferType == protocol.TransferTypeStream {
 		return NewStreamReader(reader)
 	}
diff --git a/common/buf/multi_buffer.go b/common/buf/multi_buffer.go
index b2814e5f8..2c8e95858 100644
--- a/common/buf/multi_buffer.go
+++ b/common/buf/multi_buffer.go
@@ -166,6 +166,11 @@ func (mb *MultiBuffer) SliceBySize(size int) MultiBuffer {
 		(*mb)[i] = nil
 	}
 	*mb = (*mb)[endIndex:]
+	if endIndex == 0 && len(*mb) > 0 {
+		b := New()
+		common.Must(b.Reset(ReadFullFrom((*mb)[0], size)))
+		return NewMultiBufferValue(b)
+	}
 	return slice
 }
 
diff --git a/common/buf/reader.go b/common/buf/reader.go
index 9b80e9bfe..124e3e3a3 100644
--- a/common/buf/reader.go
+++ b/common/buf/reader.go
@@ -124,6 +124,20 @@ func (r *BufferedReader) ReadMultiBuffer() (MultiBuffer, error) {
 	return r.stream.ReadMultiBuffer()
 }
 
+// ReadAtMost returns a MultiBuffer with at most size.
+func (r *BufferedReader) ReadAtMost(size int) (mb MultiBuffer, err error) {
+	if r.leftOver == nil {
+		r.leftOver, err = r.stream.ReadMultiBuffer()
+	}
+	if r.leftOver != nil {
+		mb = r.leftOver.SliceBySize(size)
+		if r.leftOver.IsEmpty() {
+			r.leftOver = nil
+		}
+	}
+	return
+}
+
 func (r *BufferedReader) writeToInternal(writer io.Writer) (int64, error) {
 	mbWriter := NewWriter(writer)
 	totalBytes := int64(0)