Thanks. That addon is unsupported, unfortunately. I'm guessing for a site under traffic spike; it might just result into issues. Surprisingly; I've enabled BD cache and the number of online users isn't affected by that addon.
I'm not sure how both are technically different - but I guess they work similarly by serving all the pages straight from the HDD.
Not quite,
This addon caches the fully rendered page and re-displays it when its requested again.