Are you running Ansible 1.5 or later? If so, you may not need accelerate mode due to a new feature called "SSH pipelining"
For users on 1.5 and later, accelerate mode only makes sense if you are (A) are managing from an Enterprise Linux 6 or earlier host
and still are on paramiko, or (B) can't enable TTYs with sudo as described in the pipelining section of
ref:`intro_configuration`.
If you can use it, the pipelining feature in Ansible reduces the amount of files transferred over the wire,
making everything much more efficient. If you can enable pipelining in ansible.cfg, it is
preferable to accelerate mode in most cases and requires fewer moving parts. Accelerate mode remains around in support of EL6
control machines and other constrained environments.
While OpenSSH using the ControlPersist feature is quite fast and scalable, there is a certain small amount of overhead involved in
using SSH connections. While many people will not encounter a need, if you are running on a platform that doesn't have ControlPersist support (such as an EL6 control machine), you'll probably be even more interested in tuning options.