ReActivity is a Mac application designed to help you test the loading speed of your website. This program immediately analyzes your webpage and spots any large document, code or third-party plugin that could possibly slow down the loading speed of the page.
So, the app doesn't really require a built-in help guide to learn how to handle ReActivity. You can easily get the answers you need, even if you're an average computer user.
Other than that, not much more can be said about this application. It does exactly what's being stated on its homepage, uses minimum CPU resources while inspecting your website, and is very simple to use.
In conclusion, you should definitely install this program on your Mac if you ever experience slow loading speed on your website and wish to know what's causing the problem. Plus, this app is free of charge.