diff --git a/src/calibre/srv/tests/web_sockets.py b/src/calibre/srv/tests/web_sockets.py
index c4fc4dca1d..bcb92d2d16 100644
--- a/src/calibre/srv/tests/web_sockets.py
+++ b/src/calibre/srv/tests/web_sockets.py
@@ -91,9 +91,9 @@ class WSClient(object):
             raise ValueError('Got a frame with mask bit set from the server')
         payload_length = b2 & 0b01111111
         if payload_length == 126:
-            payload_length = struct.unpack(b'!H', self.read_size(2))
+            payload_length = struct.unpack(b'!H', self.read_size(2))[0]
         elif payload_length == 127:
-            payload_length = struct.unpack(b'!Q', self.read_size(8))
+            payload_length = struct.unpack(b'!Q', self.read_size(8))[0]
         return Frame(fin, opcode, self.read_size(payload_length))
 
     def read_message(self):
@@ -182,7 +182,7 @@ class WSTestServer(TestServer):
     def ws_handler(self):
         return self.loop.handler.websocket_handler
 
-    def ws_connect(self):
+    def connect(self):
         return WSClient(self.address[1])
 
 class WebSocketTest(BaseTest):
@@ -208,6 +208,9 @@ class WebSocketTest(BaseTest):
         'Test basic interaction with the websocket server'
 
         with WSTestServer(EchoHandler) as server:
-            client = server.ws_connect()
-            st = partial(self.simple_test, client)
-            st([''], [''])
+            for q in ('', '*' * 125, '*' * 126, '*' * 127, '*' * 128, '*' * 65535, '*' * 65536):
+                client = server.connect()
+                self.simple_test(client, [q], [q])
+            for q in (b'', b'\xfe' * 125, b'\xfe' * 126, b'\xfe' * 127, b'\xfe' * 128, b'\xfe' * 65535, b'\xfe' * 65536):
+                client = server.connect()
+                self.simple_test(client, [q], [q])
diff --git a/src/calibre/srv/web_socket.py b/src/calibre/srv/web_socket.py
index 1fe9bd1539..7d3939e424 100644
--- a/src/calibre/srv/web_socket.py
+++ b/src/calibre/srv/web_socket.py
@@ -5,7 +5,7 @@
 from __future__ import (unicode_literals, division, absolute_import,
                         print_function)
 
-import codecs, httplib, struct, os, weakref, repr as reprlib, time
+import codecs, httplib, struct, os, weakref, repr as reprlib, time, socket
 from base64 import standard_b64encode
 from functools import partial
 from hashlib import sha1
@@ -128,9 +128,12 @@ class ReadFrame(object):  # {{{
                 return
         else:
             data = b''
-        unmasked = bytes(bytearray(ord(byte) ^ self.mask[(self.pos + i) & 3] for i, byte in enumerate(data)))
+        data = bytearray(data)
+        for i in xrange(len(data)):
+            data[i] ^= self.mask[(self.pos + i) & 3]
+        data = bytes(data)
         self.pos += len(data)
-        conn.ws_data_received(unmasked, self.opcode, self.frame_starting, self.pos >= self.payload_length, bool(self.fin))
+        conn.ws_data_received(data, self.opcode, self.frame_starting, self.pos >= self.payload_length, bool(self.fin))
         self.frame_starting = False
 # }}}
 
@@ -229,6 +232,7 @@ class WebSocketConnection(HTTPConnection):
 
         response = HANDSHAKE_STR % standard_b64encode(sha1(key + GUID_STR).digest())
         self.optimize_for_sending_packet()
+        self.socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
         self.set_state(WRITE, self.upgrade_connection_to_ws, BytesIO(response.encode('ascii')), inheaders)
 
     def upgrade_connection_to_ws(self, buf, inheaders, event):
@@ -243,6 +247,7 @@ class WebSocketConnection(HTTPConnection):
                 self.log.exception('Error in WebSockets upgrade handler:')
                 self.websocket_close(UNEXPECTED_ERROR, 'Unexpected error in handler: %r' % as_unicode(err))
             self.set_ws_state()
+            self.end_send_optimization()
 
     def set_ws_state(self):
         if self.ws_close_sent or self.ws_close_received:
@@ -295,9 +300,11 @@ class WebSocketConnection(HTTPConnection):
                     self.websocket_close(UNEXPECTED_ERROR, 'Unexpected error in handler: %r' % as_unicode(err))
                 self.current_recv_opcode = opcode
                 message_starting = True
+        if frame_finished:
+            self.current_recv_frame = ReadFrame()
         message_finished = frame_finished and is_final_frame_of_message
         if message_finished:
-            self.current_recv_frame, self.current_recv_opcode = ReadFrame(), None
+            self.current_recv_opcode = None
         if opcode == TEXT:
             if message_starting:
                 self.frag_decoder.reset()
@@ -343,6 +350,7 @@ class WebSocketConnection(HTTPConnection):
             return
         if self.send_buf is not None:
             if self.write(self.send_buf):
+                self.end_send_optimization()
                 if getattr(self.send_buf, 'is_close_frame', False):
                     self.ws_close_sent = True
                 self.send_buf = None
@@ -355,6 +363,8 @@ class WebSocketConnection(HTTPConnection):
                         self.send_buf = self.sending.create_frame()
                         if self.send_buf is None:
                             self.sending = None
+            if self.send_buf is not None:
+                self.optimize_for_sending_packet()
 
     def close(self):
         if self.in_websocket_mode: