It reads a business's own website. It starts at the page given as the business's website, usually its home page, or at the site's front page if that page cannot be read. It then reads up to four more pages of the same site that the first page links to, such as its contact, about, menu, services, prices or booking pages.
It reads the site's robots.txt first, and fetches only the pages it allows. For these pages, and for robots.txt, it sends at most one request a second to any one host name, and waits longer between them if robots.txt sets a Crawl-delay, up to 10 seconds.
If Lumefront measures how fast a home page loads, it does so with Google's PageSpeed Insights, which loads the page from Google's own servers once LumefrontBot has read it.