bbPress.org

If it’s taking 15 seconds to do add a reply or a topic you most definately have a plugin or theme manipulating post queries, most likely pre_get_posts filter is running in a plugin, maybe a theme.

Please disable ALL our plugins and test the speed again please.

If the speed remains the same, try switching to the Twenty Fourteen theme.

You’ll also notice here on bbpress.org it does not take 15 seconds