Long time to update posts

Hi there.

we’ve noticed wp is taking too much time when someone clicks the ‘update’ button for a post, also in creating new posts. I’ve deactivate all the plugins and let only this one, with the same result!

Anyway to know if it exist some conflicts with the theme?
How can I know where is the problem?

We’re using wp 3.6.1

Thank you, amigos!

http://wordpress.org/plugins/co-authors-plus/