diff --git a/dnstt-client/main.go b/dnstt-client/main.go
index a2e8f77..1b4e672 100644
--- a/dnstt-client/main.go
+++ b/dnstt-client/main.go
@@ -153,6 +153,7 @@ func run(pubkey []byte, domain dns.Name, localAddr *net.TCPAddr, remoteAddr net.
 		0, // default resend
 		1, // nc=1 => congestion window off
 	)
+	conn.SetWindowSize(turbotunnel.QueueSize/2, turbotunnel.QueueSize/2)
 	if rc := conn.SetMtu(mtu); !rc {
 		panic(rc)
 	}
@@ -167,6 +168,7 @@ func run(pubkey []byte, domain dns.Name, localAddr *net.TCPAddr, remoteAddr net.
 	smuxConfig := smux.DefaultConfig()
 	smuxConfig.Version = 2
 	smuxConfig.KeepAliveTimeout = idleTimeout
+	smuxConfig.MaxStreamBuffer = 1 * 1024 * 1024 // default is 65536
 	sess, err := smux.Client(rw, smuxConfig)
 	if err != nil {
 		return fmt.Errorf("opening smux session: %v", err)
diff --git a/dnstt-server/main.go b/dnstt-server/main.go
index 8771fef..35a997e 100644
--- a/dnstt-server/main.go
+++ b/dnstt-server/main.go
@@ -241,6 +241,7 @@ func acceptStreams(conn *kcp.UDPSession, privkey []byte, upstream string) error
 	smuxConfig := smux.DefaultConfig()
 	smuxConfig.Version = 2
 	smuxConfig.KeepAliveTimeout = idleTimeout
+	smuxConfig.MaxStreamBuffer = 1 * 1024 * 1024 // default is 65536
 	sess, err := smux.Server(rw, smuxConfig)
 	if err != nil {
 		return err
@@ -291,6 +292,7 @@ func acceptSessions(ln *kcp.Listener, privkey []byte, mtu int, upstream string)
 			0, // default resend
 			1, // nc=1 => congestion window off
 		)
+		conn.SetWindowSize(turbotunnel.QueueSize/2, turbotunnel.QueueSize/2)
 		if rc := conn.SetMtu(mtu); !rc {
 			panic(rc)
 		}
diff --git a/turbotunnel/consts.go b/turbotunnel/consts.go
index db54589..5684bf7 100644
--- a/turbotunnel/consts.go
+++ b/turbotunnel/consts.go
@@ -6,7 +6,9 @@ package turbotunnel
 
 import "errors"
 
-const queueSize = 64
+// QueueSize is the size of send and receive queues in QueuePacketConn and
+// RemoteMap.
+const QueueSize = 128
 
 var errClosedPacketConn = errors.New("operation on closed connection")
 var errNotImplemented = errors.New("not implemented")
diff --git a/turbotunnel/queuepacketconn.go b/turbotunnel/queuepacketconn.go
index eb4df4b..6571de0 100644
--- a/turbotunnel/queuepacketconn.go
+++ b/turbotunnel/queuepacketconn.go
@@ -48,7 +48,7 @@ func NewQueuePacketConn(localAddr net.Addr, timeout time.Duration) *QueuePacketC
 	return &QueuePacketConn{
 		remotes:   NewRemoteMap(timeout),
 		localAddr: localAddr,
-		recvQueue: make(chan taggedPacket, queueSize),
+		recvQueue: make(chan taggedPacket, QueueSize),
 		closed:    make(chan struct{}),
 	}
 }
diff --git a/turbotunnel/remotemap.go b/turbotunnel/remotemap.go
index c679bfa..a3238e9 100644
--- a/turbotunnel/remotemap.go
+++ b/turbotunnel/remotemap.go
@@ -127,7 +127,7 @@ func (inner *remoteMapInner) Lookup(addr net.Addr, now time.Time) *remoteRecord
 		record = &remoteRecord{
 			Addr:      addr,
 			LastSeen:  now,
-			SendQueue: make(chan []byte, queueSize),
+			SendQueue: make(chan []byte, QueueSize),
 			Stash:     make(chan []byte, 1),
 		}
 		heap.Push(inner, record)