diff --git a/CHANGES/2126.feature b/CHANGES/2126.feature
new file mode 100644
index 00000000000..ee2562d7df6
--- /dev/null
+++ b/CHANGES/2126.feature
@@ -0,0 +1 @@
+Speed up the `PayloadWriter.write` method for large request bodies.
diff --git a/aiohttp/http_writer.py b/aiohttp/http_writer.py
index f8da95074c2..03869c44e5e 100644
--- a/aiohttp/http_writer.py
+++ b/aiohttp/http_writer.py
@@ -125,6 +125,7 @@ class PayloadWriter(AbstractPayloadWriter):
     def __init__(self, stream, loop, acquire=True):
         self._stream = stream
         self._transport = None
+        self._buffer = []
 
         self.loop = loop
         self.length = None
@@ -133,12 +134,12 @@ def __init__(self, stream, loop, acquire=True):
         self.output_size = 0
 
         self._eof = False
-        self._buffer = []
         self._compress = None
         self._drain_waiter = None
 
         if self._stream.available:
             self._transport = self._stream.transport
+            self._buffer = None
             self._stream.available = False
         elif acquire:
             self._stream.acquire(self)
@@ -146,15 +147,22 @@ def __init__(self, stream, loop, acquire=True):
     def set_transport(self, transport):
         self._transport = transport
 
-        chunk = b''.join(self._buffer)
-        if chunk:
-            transport.write(chunk)
-            self._buffer.clear()
+        if self._buffer is not None:
+            for chunk in self._buffer:
+                transport.write(chunk)
+            self._buffer = None
 
         if self._drain_waiter is not None:
             waiter, self._drain_waiter = self._drain_waiter, None
-            if not waiter.done():
-                waiter.set_result(None)
+            waiter.set_result(None)
+
+    async def get_transport(self):
+        if self._transport is None:
+            if self._drain_waiter is None:
+                self._drain_waiter = self.loop.create_future()
+            await self._drain_waiter
+
+        return self._transport
 
     @property
     def tcp_nodelay(self):
@@ -178,25 +186,14 @@ def enable_compression(self, encoding='deflate'):
                      if encoding == 'gzip' else -zlib.MAX_WBITS)
         self._compress = zlib.compressobj(wbits=zlib_mode)
 
-    def buffer_data(self, chunk):
-        if chunk:
-            size = len(chunk)
-            self.buffer_size += size
-            self.output_size += size
-            self._buffer.append(chunk)
-
     def _write(self, chunk):
         size = len(chunk)
         self.buffer_size += size
         self.output_size += size
 
+        # see set_transport: exactly one of _buffer or _transport is None
         if self._transport is not None:
-            if self._buffer:
-                self._buffer.append(chunk)
-                self._transport.write(b''.join(self._buffer))
-                self._buffer.clear()
-            else:
-                self._transport.write(chunk)
+            self._transport.write(chunk)
         else:
             self._buffer.append(chunk)
 
@@ -241,11 +238,7 @@ def write_headers(self, status_line, headers, SEP=': ', END='\r\n'):
         headers = status_line + ''.join(
             [k + SEP + v + END for k, v in headers.items()])
         headers = headers.encode('utf-8') + b'\r\n'
-
-        size = len(headers)
-        self.buffer_size += size
-        self.output_size += size
-        self._buffer.append(headers)
+        self._write(headers)
 
     async def write_eof(self, chunk=b''):
         if self._eof:
@@ -268,24 +261,17 @@ async def write_eof(self, chunk=b''):
                     chunk = b'0\r\n\r\n'
 
         if chunk:
-            self.buffer_data(chunk)
+            self._write(chunk)
 
-        await self.drain(True)
+        await self.drain()
 
         self._eof = True
         self._transport = None
         self._stream.release()
 
-    async def drain(self, last=False):
+    async def drain(self):
         if self._transport is not None:
-            if self._buffer:
-                self._transport.write(b''.join(self._buffer))
-                if not last:
-                    self._buffer.clear()
             await self._stream.drain()
         else:
             # wait for transport
-            if self._drain_waiter is None:
-                self._drain_waiter = self.loop.create_future()
-
-            await self._drain_waiter
+            await self.get_transport()
diff --git a/aiohttp/web_fileresponse.py b/aiohttp/web_fileresponse.py
index 7ef19bb8931..fdb68916ebf 100644
--- a/aiohttp/web_fileresponse.py
+++ b/aiohttp/web_fileresponse.py
@@ -18,17 +18,16 @@
 
 class SendfilePayloadWriter(PayloadWriter):
 
-    def set_transport(self, transport):
-        self._transport = transport
-
-        if self._drain_waiter is not None:
-            waiter, self._drain_maiter = self._drain_maiter, None
-            if not waiter.done():
-                waiter.set_result(None)
+    def __init__(self, *args, **kwargs):
+        self._sendfile_buffer = []
+        super().__init__(*args, **kwargs)
 
     def _write(self, chunk):
+        # we overwrite PayloadWriter._write, so nothing can be appended to
+        # _buffer, and nothing is written to the transport directly by the
+        # parent class
         self.output_size += len(chunk)
-        self._buffer.append(chunk)
+        self._sendfile_buffer.append(chunk)
 
     def _sendfile_cb(self, fut, out_fd, in_fd,
                      offset, count, loop, registered):
@@ -54,33 +53,29 @@ def _sendfile_cb(self, fut, out_fd, in_fd,
             fut.set_result(None)
 
     async def sendfile(self, fobj, count):
-        if self._transport is None:
-            if self._drain_waiter is None:
-                self._drain_waiter = self.loop.create_future()
-
-            await self._drain_waiter
+        transport = await self.get_transport()
 
-        out_socket = self._transport.get_extra_info("socket").dup()
+        out_socket = transport.get_extra_info('socket').dup()
         out_socket.setblocking(False)
         out_fd = out_socket.fileno()
         in_fd = fobj.fileno()
         offset = fobj.tell()
 
         loop = self.loop
+        data = b''.join(self._sendfile_buffer)
         try:
-            await loop.sock_sendall(out_socket, b''.join(self._buffer))
+            await loop.sock_sendall(out_socket, data)
             fut = loop.create_future()
             self._sendfile_cb(fut, out_fd, in_fd, offset, count, loop, False)
             await fut
         except Exception:
             server_logger.debug('Socket error')
-            self._transport.close()
+            transport.close()
         finally:
             out_socket.close()
 
         self.output_size += count
-        self._transport = None
-        self._stream.release()
+        await super().write_eof()
 
     async def write_eof(self, chunk=b''):
         pass
diff --git a/tests/test_client_functional.py b/tests/test_client_functional.py
index e0377d2d146..60215de1f56 100644
--- a/tests/test_client_functional.py
+++ b/tests/test_client_functional.py
@@ -1694,6 +1694,27 @@ async def handler(request):
     resp.close()
 
 
+async def test_encoding_gzip_write_by_chunks(loop, test_client):
+
+    async def handler(request):
+        resp = web.StreamResponse()
+        resp.enable_compression(web.ContentCoding.gzip)
+        await resp.prepare(request)
+        await resp.write(b'0')
+        await resp.write(b'0')
+        return resp
+
+    app = web.Application()
+    app.router.add_get('/', handler)
+    client = await test_client(app)
+
+    resp = await client.get('/')
+    assert 200 == resp.status
+    txt = await resp.text()
+    assert txt == '00'
+    resp.close()
+
+
 async def test_encoding_gzip_nochunk(loop, test_client):
 
     async def handler(request):
@@ -1778,6 +1799,26 @@ async def handler(request):
     resp.close()
 
 
+async def test_payload_content_length_by_chunks(loop, test_client):
+
+    async def handler(request):
+        resp = web.StreamResponse(headers={'content-length': '3'})
+        await resp.prepare(request)
+        await resp.write(b'answer')
+        await resp.write(b'two')
+        request.transport.close()
+        return resp
+
+    app = web.Application()
+    app.router.add_get('/', handler)
+    client = await test_client(app)
+
+    resp = await client.get('/')
+    data = await resp.read()
+    assert data == b'ans'
+    resp.close()
+
+
 async def test_chunked(loop, test_client):
 
     async def handler(request):
@@ -2462,7 +2503,7 @@ def connection_lost(self, exc):
     await r.read()
     assert 1 == len(connector._conns)
 
-    with pytest.raises(aiohttp.ServerDisconnectedError):
+    with pytest.raises(aiohttp.ClientConnectionError):
         await session.request('GET', url)
     assert 0 == len(connector._conns)
 
diff --git a/tests/test_http_writer.py b/tests/test_http_writer.py
index ac5280fc391..3530abcc7e8 100644
--- a/tests/test_http_writer.py
+++ b/tests/test_http_writer.py
@@ -1,5 +1,6 @@
 """Tests for aiohttp/http_writer.py"""
 
+import asyncio
 import zlib
 from unittest import mock
 
@@ -148,3 +149,19 @@ def test_write_drain(stream, loop):
     msg.write(b'1', drain=True)
     assert msg.drain.called
     assert msg.buffer_size == 0
+
+
+async def test_multiple_drains(stream, loop):
+    stream.available = False
+    msg = http.PayloadWriter(stream, loop)
+    fut1 = loop.create_task(msg.drain())
+    fut2 = loop.create_task(msg.drain())
+
+    assert not fut1.done()
+    assert not fut2.done()
+
+    msg.set_transport(stream.transport)
+
+    await asyncio.sleep(0)
+    assert fut1.done()
+    assert fut2.done()
diff --git a/tests/test_web_server.py b/tests/test_web_server.py
index b8284502d3c..3561dae504d 100644
--- a/tests/test_web_server.py
+++ b/tests/test_web_server.py
@@ -80,8 +80,9 @@ async def handler(request):
     server = await raw_test_server(handler, logger=logger)
     cli = await test_client(server)
 
-    with pytest.raises(client.ServerDisconnectedError):
-        await cli.get('/path/to')
+    resp = await cli.get('/path/to')
+    with pytest.raises(client.ClientPayloadError):
+        await resp.read()
 
     logger.debug.assert_called_with('Ignored premature client disconnection ')