The release has many optimizations as well as other improvements and bug fixes.

The most notable ones:

• Use TCP_CORK/TCP_NOPUSH and TCP_NODELAY for disabling Nagle algorithm
• Reduce amount of syscalls for chunked encoding transfer
• Improve performance of websocket mask applying
• Round server timeouts to seconds for grouping pending calls
• Implement Class Based Views
• Fix broken support for https proxies with authentication

Full list of changes:

• Extend list of web exceptions, add HTTPMisdirectedRequest,
  HTTPUpgradeRequired, HTTPPreconditionRequired, HTTPTooManyRequests,
  HTTPRequestHeaderFieldsTooLarge, HTTPVariantAlsoNegotiates,
  HTTPNotExtended, HTTPNetworkAuthenticationRequired status codes #644
• Do not remove AUTHORIZATION header by WSGI handler #649
• Fix broken support for https proxies with authentication #617
• Get REMOTE_* and SEVER_* http vars from headers when listening on
  unix socket #654
• Add HTTP 308 support #663
• Add Tf format (time to serve request in seconds, %06f format) to
  access log #669
• Remove one and a half years long deprecated
  ClientResponse.read_and_close() method
• Optimize chunked encoding: use a single syscall instead of 3 calls
  on sending chunked encoded data
• Use TCP_CORK and TCP_NODELAY to optimize network latency and
  throughput #680
• Websocket XOR performance improved #687
• Avoid sending cookie attributes in Cookie header #613
• Round server timeouts to second for grouping pending call. That
  leads to less amount of poller syscalls e.g epoll.poll(). #702
• Close connection on websocket handshake error #703
• Implement class based views #684
• Add headers parameter to ws_connect() #709
• Drop unused function parse_remote_addr() #708
• Close session on exception #707
• Store http code and headers in WSServerHandshakeError #706
• Make some low-level message properties readonly #710