In recent Ansible update to 1.5 version there is really nice feature ssh pipelining. This option is serious alternative to accelerated mode.
Just add to you config file (ex. ~/.ansible.cfg):
[ssh_connection]
pipelining=True
Now run any playbook - you will see the difference 😄
Source (and extended info about):
http://blog.ansibleworks.com/2014/01/15/ssh-connection-upgrades-coming-in-ansible-1-5/