I have a bunch of playbooks that still use 1.8 and they are dog slow. Changing the contents of one file can take ~10 minutes. (Interestingly, running the entire playbook on a clean server is actually faster).
O_o
That kind of simple operation just zipped by for me on Ansible 1.6, 1.8, 1.9, and 2.0. The only noticeably slow kinds of operations for me are generally the package installs (understandably). I don't use a ton of variables in my templates, though.
{% for cred in credentials %}
{{cred.key}}: {{cred.value}}
{% endfor %} {{ credentials | to_nice_json }}the only answer i can give you is: test.
We do try to keep decent performance, but this is not our main focus.