Anyone know how supercache preloads?

Hello! Had the same problem! It would be plugin conflict. Try disabling all the plugins except WP super cache and preload again! It should normally preload about 71 pages (about 6.9 MBs) in 5 minutes! It worked fine in my occasion!

By the way preloading is a great feature! My site loads superfast and page to page navigation is also fast enough! I am on a shared server!