You implement a Decider on your page by copying and pasting one line of HTML (for the button) and one line of javascript (to display the Decider when the button is clicked).  Deciders are implemented as client-side javascript, they load once with your page and that’s it.  There is no back and forth traffic between the user’s browser and web server so the decider loads and works super fast.  The Decider becomes part of your web page.

The javascript for Deciders loads asynchronously (concurrently with your own site code and won’t block usage of your page) so there is no impact on the time it takes your page to load.  The Decider button will display on your page as soon as the javascript is finished loading.  After that, use of the Decider is instantaneous.

The short answer is 5.  For more details, see our “How long should a list be” and “People Buy Less With Too Many Choices” blog posts.