diff --git a/connector/ss/udp/connector.go b/connector/ss/udp/connector.go
index f89531a6..ae98b999 100644
--- a/connector/ss/udp/connector.go
+++ b/connector/ss/udp/connector.go
@@ -85,7 +85,7 @@ func (c *ssuConnector) Connect(ctx context.Context, conn net.Conn, network, addr
 		}
 
 		// standard UDP relay
-		return ss.UDPClientConn(pc, conn.RemoteAddr(), taddr, c.md.bufferSize), nil
+		return ss.UDPClientConn(pc, conn.RemoteAddr(), taddr), nil
 	}
 
 	if c.cipher != nil {
diff --git a/connector/ss/udp/metadata.go b/connector/ss/udp/metadata.go
index 16378875..5227b1a5 100644
--- a/connector/ss/udp/metadata.go
+++ b/connector/ss/udp/metadata.go
@@ -1,7 +1,6 @@
 package ss
 
 import (
-	"math"
 	"time"
 
 	mdata "github.com/go-gost/core/metadata"
@@ -11,24 +10,16 @@ import (
 type metadata struct {
 	key            string
 	connectTimeout time.Duration
-	bufferSize     int
 }
 
 func (c *ssuConnector) parseMetadata(md mdata.Metadata) (err error) {
 	const (
 		key            = "key"
 		connectTimeout = "timeout"
-		bufferSize     = "bufferSize" // udp buffer size
 	)
 
 	c.md.key = mdutil.GetString(md, key)
 	c.md.connectTimeout = mdutil.GetDuration(md, connectTimeout)
 
-	if bs := mdutil.GetInt(md, bufferSize); bs > 0 {
-		c.md.bufferSize = int(math.Min(math.Max(float64(bs), 512), 64*1024))
-	} else {
-		c.md.bufferSize = 4096
-	}
-
 	return
 }
diff --git a/handler/http/handler.go b/handler/http/handler.go
index 89b0b98e..4a9dd461 100644
--- a/handler/http/handler.go
+++ b/handler/http/handler.go
@@ -288,9 +288,6 @@ func (h *httpHandler) handleRequest(ctx context.Context, conn net.Conn, req *htt
 		return errors.New("authentication failed")
 	}
 
-	if resp.Header == nil {
-		resp.Header = http.Header{}
-	}
 	if resp.Header.Get("Proxy-Agent") == "" {
 		resp.Header.Set("Proxy-Agent", h.md.proxyAgent)
 	}
diff --git a/handler/ss/udp/handler.go b/handler/ss/udp/handler.go
index 7395d570..f00693b0 100644
--- a/handler/ss/udp/handler.go
+++ b/handler/ss/udp/handler.go
@@ -7,7 +7,6 @@ import (
 	"net"
 	"time"
 
-	"github.com/go-gost/core/common/bufpool"
 	"github.com/go-gost/core/handler"
 	"github.com/go-gost/core/logger"
 	md "github.com/go-gost/core/metadata"
@@ -111,7 +110,7 @@ func (h *ssuHandler) Handle(ctx context.Context, conn net.Conn, opts ...handler.
 			pc = h.cipher.PacketConn(pc)
 		}
 		// standard UDP relay.
-		pc = ss.UDPServerConn(pc, conn.RemoteAddr(), h.md.bufferSize)
+		pc = ss.UDPServerConn(pc, conn.RemoteAddr())
 	} else {
 		if h.cipher != nil {
 			conn = ss.ShadowConn(h.cipher.StreamConn(conn), nil)
@@ -147,16 +146,13 @@ func (h *ssuHandler) Handle(ctx context.Context, conn net.Conn, opts ...handler.
 }
 
 func (h *ssuHandler) relayPacket(ctx context.Context, pc1, pc2 net.PacketConn, ro *xrecorder.HandlerRecorderObject, log logger.Logger) (err error) {
-	bufSize := h.md.bufferSize
 	errc := make(chan error, 2)
 
 	go func() {
+		var b [MaxMessageSize]byte
 		for {
 			err := func() error {
-				b := bufpool.Get(bufSize)
-				defer bufpool.Put(b)
-
-				n, addr, err := pc1.ReadFrom(b)
+				n, addr, err := pc1.ReadFrom(b[:])
 				if err != nil {
 					return err
 				}
@@ -187,12 +183,10 @@ func (h *ssuHandler) relayPacket(ctx context.Context, pc1, pc2 net.PacketConn, r
 	}()
 
 	go func() {
+		var b [MaxMessageSize]byte
 		for {
 			err := func() error {
-				b := bufpool.Get(bufSize)
-				defer bufpool.Put(b)
-
-				n, raddr, err := pc2.ReadFrom(b)
+				n, raddr, err := pc2.ReadFrom(b[:])
 				if err != nil {
 					return err
 				}
diff --git a/handler/ss/udp/metadata.go b/handler/ss/udp/metadata.go
index 76408bd3..33145e84 100644
--- a/handler/ss/udp/metadata.go
+++ b/handler/ss/udp/metadata.go
@@ -8,26 +8,23 @@ import (
 	mdutil "github.com/go-gost/x/metadata/util"
 )
 
+const (
+	MaxMessageSize = math.MaxUint16
+)
+
 type metadata struct {
 	key         string
 	readTimeout time.Duration
-	bufferSize  int
 }
 
 func (h *ssuHandler) parseMetadata(md mdata.Metadata) (err error) {
 	const (
 		key         = "key"
 		readTimeout = "readTimeout"
-		bufferSize  = "bufferSize"
 	)
 
 	h.md.key = mdutil.GetString(md, key)
 	h.md.readTimeout = mdutil.GetDuration(md, readTimeout)
 
-	if bs := mdutil.GetInt(md, bufferSize); bs > 0 {
-		h.md.bufferSize = int(math.Min(math.Max(float64(bs), 512), 64*1024))
-	} else {
-		h.md.bufferSize = 4096
-	}
 	return
 }
diff --git a/handler/tap/handler.go b/handler/tap/handler.go
index e1ab956e..79785732 100644
--- a/handler/tap/handler.go
+++ b/handler/tap/handler.go
@@ -11,17 +11,16 @@ import (
 	"time"
 
 	"github.com/go-gost/core/chain"
-	"github.com/go-gost/core/common/bufpool"
 	"github.com/go-gost/core/handler"
 	"github.com/go-gost/core/hop"
 	"github.com/go-gost/core/logger"
 	md "github.com/go-gost/core/metadata"
+	ctxvalue "github.com/go-gost/x/ctx"
 	"github.com/go-gost/x/internal/util/ss"
 	tap_util "github.com/go-gost/x/internal/util/tap"
 	"github.com/go-gost/x/registry"
 	"github.com/shadowsocks/go-shadowsocks2/core"
 	"github.com/shadowsocks/go-shadowsocks2/shadowaead"
-	ctxvalue "github.com/go-gost/x/ctx"
 	"github.com/songgao/water/waterutil"
 )
 
@@ -187,12 +186,10 @@ func (h *tapHandler) transport(tap net.Conn, conn net.PacketConn, raddr net.Addr
 	errc := make(chan error, 1)
 
 	go func() {
+		var b [MaxMessageSize]byte
 		for {
 			err := func() error {
-				b := bufpool.Get(h.md.bufferSize)
-				defer bufpool.Put(b)
-
-				n, err := tap.Read(b)
+				n, err := tap.Read(b[:])
 				if err != nil {
 					select {
 					case h.exit <- struct{}{}:
@@ -249,12 +246,10 @@ func (h *tapHandler) transport(tap net.Conn, conn net.PacketConn, raddr net.Addr
 	}()
 
 	go func() {
+		var b [MaxMessageSize]byte
 		for {
 			err := func() error {
-				b := bufpool.Get(h.md.bufferSize)
-				defer bufpool.Put(b)
-
-				n, addr, err := conn.ReadFrom(b)
+				n, addr, err := conn.ReadFrom(b[:])
 				if err != nil &&
 					err != shadowaead.ErrShortPacket {
 					return err
diff --git a/handler/tap/metadata.go b/handler/tap/metadata.go
index 11125fba..262d4e19 100644
--- a/handler/tap/metadata.go
+++ b/handler/tap/metadata.go
@@ -1,25 +1,25 @@
 package tap
 
 import (
+	"math"
+
 	mdata "github.com/go-gost/core/metadata"
 	mdutil "github.com/go-gost/x/metadata/util"
 )
 
+const (
+	MaxMessageSize = math.MaxUint16
+)
+
 type metadata struct {
-	key        string
-	bufferSize int
+	key string
 }
 
 func (h *tapHandler) parseMetadata(md mdata.Metadata) (err error) {
 	const (
-		key        = "key"
-		bufferSize = "bufferSize"
+		key = "key"
 	)
 
 	h.md.key = mdutil.GetString(md, key)
-	h.md.bufferSize = mdutil.GetInt(md, bufferSize)
-	if h.md.bufferSize <= 0 {
-		h.md.bufferSize = 4096
-	}
 	return
 }
diff --git a/handler/tun/client.go b/handler/tun/client.go
index af281584..7b8250fa 100644
--- a/handler/tun/client.go
+++ b/handler/tun/client.go
@@ -103,12 +103,10 @@ func (h *tunHandler) transportClient(ctx context.Context, tun io.ReadWriter, con
 	errc := make(chan error, 2)
 
 	go func() {
+		var b [MaxMessageSize]byte
 		for {
 			err := func() error {
-				b := bufpool.Get(h.md.bufferSize)
-				defer bufpool.Put(b)
-
-				n, err := tun.Read(b)
+				n, err := tun.Read(b[:])
 				if err != nil {
 					return fmt.Errorf("%w: read: %s", ErrTun, err.Error())
 				}
@@ -155,12 +153,10 @@ func (h *tunHandler) transportClient(ctx context.Context, tun io.ReadWriter, con
 	}()
 
 	go func() {
+		var b [MaxMessageSize]byte
 		for {
 			err := func() error {
-				b := bufpool.Get(h.md.bufferSize)
-				defer bufpool.Put(b)
-
-				n, err := conn.Read(b)
+				n, err := conn.Read(b[:])
 				if err != nil {
 					return err
 				}
@@ -175,7 +171,7 @@ func (h *tunHandler) transportClient(ctx context.Context, tun io.ReadWriter, con
 					return nil
 				}
 
-				if waterutil.IsIPv4(b) {
+				if waterutil.IsIPv4(b[:n]) {
 					header, err := ipv4.ParseHeader(b[:n])
 					if err != nil {
 						log.Warn(err)
diff --git a/handler/tun/metadata.go b/handler/tun/metadata.go
index 926ae165..06186ff4 100644
--- a/handler/tun/metadata.go
+++ b/handler/tun/metadata.go
@@ -1,6 +1,7 @@
 package tun
 
 import (
+	"math"
 	"time"
 
 	mdata "github.com/go-gost/core/metadata"
@@ -9,22 +10,16 @@ import (
 
 const (
 	defaultKeepAlivePeriod = 10 * time.Second
-	defaultBufferSize      = 4096
+	MaxMessageSize         = math.MaxUint16
 )
 
 type metadata struct {
-	bufferSize      int
 	keepAlivePeriod time.Duration
 	passphrase      string
 	p2p             bool
 }
 
 func (h *tunHandler) parseMetadata(md mdata.Metadata) (err error) {
-	h.md.bufferSize = mdutil.GetInt(md, "tun.bufsize", "bufsize", "buffersize")
-	if h.md.bufferSize <= 0 {
-		h.md.bufferSize = defaultBufferSize
-	}
-
 	if mdutil.GetBool(md, "tun.keepalive", "keepalive") {
 		h.md.keepAlivePeriod = mdutil.GetDuration(md, "tun.ttl", "ttl")
 		if h.md.keepAlivePeriod <= 0 {
diff --git a/handler/tun/server.go b/handler/tun/server.go
index 9c23cc3e..659718d9 100644
--- a/handler/tun/server.go
+++ b/handler/tun/server.go
@@ -8,7 +8,6 @@ import (
 	"net/netip"
 	"time"
 
-	"github.com/go-gost/core/common/bufpool"
 	"github.com/go-gost/core/logger"
 	"github.com/go-gost/core/router"
 	xip "github.com/go-gost/x/internal/net/ip"
@@ -42,12 +41,10 @@ func (h *tunHandler) transportServer(ctx context.Context, tun io.ReadWriter, con
 	errc := make(chan error, 1)
 
 	go func() {
+		var b [MaxMessageSize]byte
 		for {
 			err := func() error {
-				b := bufpool.Get(h.md.bufferSize)
-				defer bufpool.Put(b)
-
-				n, err := tun.Read(b)
+				n, err := tun.Read(b[:])
 				if err != nil {
 					return ErrTun
 				}
@@ -110,12 +107,10 @@ func (h *tunHandler) transportServer(ctx context.Context, tun io.ReadWriter, con
 	}()
 
 	go func() {
+		var b [MaxMessageSize]byte
 		for {
 			err := func() error {
-				b := bufpool.Get(h.md.bufferSize)
-				defer bufpool.Put(b)
-
-				n, addr, err := conn.ReadFrom(b)
+				n, addr, err := conn.ReadFrom(b[:])
 				if err != nil {
 					return err
 				}
diff --git a/internal/net/udp/relay.go b/internal/net/udp/relay.go
index 1694ba36..c14124ab 100644
--- a/internal/net/udp/relay.go
+++ b/internal/net/udp/relay.go
@@ -2,20 +2,23 @@ package udp
 
 import (
 	"context"
+	"math"
 	"net"
 
 	"github.com/go-gost/core/bypass"
-	"github.com/go-gost/core/common/bufpool"
 	"github.com/go-gost/core/logger"
 )
 
+const (
+	MaxMessageSize = math.MaxUint16
+)
+
 type Relay struct {
 	pc1 net.PacketConn
 	pc2 net.PacketConn
 
-	bypass     bypass.Bypass
-	bufferSize int
-	logger     logger.Logger
+	bypass bypass.Bypass
+	logger logger.Logger
 }
 
 func NewRelay(pc1, pc2 net.PacketConn) *Relay {
@@ -35,25 +38,14 @@ func (r *Relay) WithLogger(logger logger.Logger) *Relay {
 	return r
 }
 
-func (r *Relay) SetBufferSize(n int) {
-	r.bufferSize = n
-}
-
 func (r *Relay) Run(ctx context.Context) (err error) {
-	bufSize := r.bufferSize
-	if bufSize <= 0 {
-		bufSize = 4096
-	}
-
 	errc := make(chan error, 2)
 
 	go func() {
+		var b [MaxMessageSize]byte
 		for {
 			err := func() error {
-				b := bufpool.Get(bufSize)
-				defer bufpool.Put(b)
-
-				n, raddr, err := r.pc1.ReadFrom(b)
+				n, raddr, err := r.pc1.ReadFrom(b[:])
 				if err != nil {
 					return err
 				}
@@ -86,12 +78,10 @@ func (r *Relay) Run(ctx context.Context) (err error) {
 	}()
 
 	go func() {
+		var b [MaxMessageSize]byte
 		for {
 			err := func() error {
-				b := bufpool.Get(bufSize)
-				defer bufpool.Put(b)
-
-				n, raddr, err := r.pc2.ReadFrom(b)
+				n, raddr, err := r.pc2.ReadFrom(b[:])
 				if err != nil {
 					return err
 				}
diff --git a/internal/util/socks/conn.go b/internal/util/socks/conn.go
index 205b5859..49a91702 100644
--- a/internal/util/socks/conn.go
+++ b/internal/util/socks/conn.go
@@ -2,9 +2,9 @@ package socks
 
 import (
 	"bytes"
+	"math"
 	"net"
 
-	"github.com/go-gost/core/common/bufpool"
 	"github.com/go-gost/gosocks5"
 )
 
@@ -85,21 +85,19 @@ func (c *udpTunConn) Write(b []byte) (n int, err error) {
 	return c.WriteTo(b, c.taddr)
 }
 
-var (
-	DefaultBufferSize = 4096
+const (
+	MaxMessageSize = math.MaxUint16
 )
 
 type udpConn struct {
 	net.PacketConn
-	raddr      net.Addr
-	taddr      net.Addr
-	bufferSize int
+	raddr net.Addr
+	taddr net.Addr
 }
 
-func UDPConn(c net.PacketConn, bufferSize int) net.PacketConn {
+func UDPConn(c net.PacketConn) net.PacketConn {
 	return &udpConn{
 		PacketConn: c,
-		bufferSize: bufferSize,
 	}
 }
 
@@ -107,10 +105,9 @@ func UDPConn(c net.PacketConn, bufferSize int) net.PacketConn {
 // NOTE: for server side,
 // the returned addr is the target address the client want to relay to.
 func (c *udpConn) ReadFrom(b []byte) (n int, addr net.Addr, err error) {
-	rbuf := bufpool.Get(c.bufferSize)
-	defer bufpool.Put(rbuf)
+	var rbuf [MaxMessageSize]byte
 
-	n, c.raddr, err = c.PacketConn.ReadFrom(rbuf)
+	n, c.raddr, err = c.PacketConn.ReadFrom(rbuf[:])
 	if err != nil {
 		return
 	}
@@ -135,8 +132,6 @@ func (c *udpConn) Read(b []byte) (n int, err error) {
 }
 
 func (c *udpConn) WriteTo(b []byte, addr net.Addr) (n int, err error) {
-	wbuf := bufpool.Get(c.bufferSize)
-	defer bufpool.Put(wbuf)
 
 	socksAddr := gosocks5.Addr{}
 	if err = socksAddr.ParseFrom(addr.String()); err != nil {
@@ -151,7 +146,8 @@ func (c *udpConn) WriteTo(b []byte, addr net.Addr) (n int, err error) {
 		Data:   b,
 	}
 
-	buf := bytes.NewBuffer(wbuf[:0])
+	var wbuf [MaxMessageSize]byte
+	buf := bytes.NewBuffer(wbuf[:][:0])
 	_, err = dgram.WriteTo(buf)
 	if err != nil {
 		return
diff --git a/internal/util/ss/conn.go b/internal/util/ss/conn.go
index c07cd10c..8627590c 100644
--- a/internal/util/ss/conn.go
+++ b/internal/util/ss/conn.go
@@ -2,14 +2,14 @@ package ss
 
 import (
 	"bytes"
+	"math"
 	"net"
 
-	"github.com/go-gost/core/common/bufpool"
 	"github.com/go-gost/gosocks5"
 )
 
-var (
-	DefaultBufferSize = 4096
+const (
+	MaxMessageSize = math.MaxUint16
 )
 
 var (
@@ -19,33 +19,29 @@ var (
 
 type UDPConn struct {
 	net.PacketConn
-	raddr      net.Addr
-	taddr      net.Addr
-	bufferSize int
+	raddr net.Addr
+	taddr net.Addr
 }
 
-func UDPClientConn(c net.PacketConn, remoteAddr, targetAddr net.Addr, bufferSize int) *UDPConn {
+func UDPClientConn(c net.PacketConn, remoteAddr, targetAddr net.Addr) *UDPConn {
 	return &UDPConn{
 		PacketConn: c,
 		raddr:      remoteAddr,
 		taddr:      targetAddr,
-		bufferSize: bufferSize,
 	}
 }
 
-func UDPServerConn(c net.PacketConn, remoteAddr net.Addr, bufferSize int) *UDPConn {
+func UDPServerConn(c net.PacketConn, remoteAddr net.Addr) *UDPConn {
 	return &UDPConn{
 		PacketConn: c,
 		raddr:      remoteAddr,
-		bufferSize: bufferSize,
 	}
 }
 
 func (c *UDPConn) ReadFrom(b []byte) (n int, addr net.Addr, err error) {
-	rbuf := bufpool.Get(c.bufferSize)
-	defer bufpool.Put(rbuf)
+	var rbuf [MaxMessageSize]byte
 
-	n, _, err = c.PacketConn.ReadFrom(rbuf)
+	n, _, err = c.PacketConn.ReadFrom(rbuf[:])
 	if err != nil {
 		return
 	}
@@ -68,15 +64,14 @@ func (c *UDPConn) Read(b []byte) (n int, err error) {
 }
 
 func (c *UDPConn) WriteTo(b []byte, addr net.Addr) (n int, err error) {
-	wbuf := bufpool.Get(c.bufferSize)
-	defer bufpool.Put(wbuf)
+	var wbuf [MaxMessageSize]byte
 
 	socksAddr := gosocks5.Addr{}
 	if err = socksAddr.ParseFrom(addr.String()); err != nil {
 		return
 	}
 
-	addrLen, err := socksAddr.Encode(wbuf)
+	addrLen, err := socksAddr.Encode(wbuf[:])
 	if err != nil {
 		return
 	}
diff --git a/listener/tap/metadata.go b/listener/tap/metadata.go
index dd2ecfc8..4d826c06 100644
--- a/listener/tap/metadata.go
+++ b/listener/tap/metadata.go
@@ -10,7 +10,7 @@ import (
 )
 
 const (
-	DefaultMTU = 1350
+	DefaultMTU = 1420
 )
 
 type metadata struct {