Originally posted by steveholt951
Since we don't know what "goals" Sidious had and since the inhabitants of Byss apparently lived out their lives fine, whether it was in a perpetual state of a valium induced high or not, it's not the same thing as getting the life sucked out of you, or destroying a planet and achieving immortality.
Byss and the Deep Core corroborates Book of Sith's claim that Sidious used the energy pool created by constantly leeching off Byss's inhabitants to perform "vile experiments" on "sentient life" to "increase his knowledge of the dark side." Sidious not leeching their life completely and simultaneously was actually very wise: by allowing the citizens to live and replenish what he took, he essentially had a perpetual battery to use for ongoing experiments until his death.
We know Sidious had already secured a means of functional immortality by way of clones and the essence transfer, so there's that. Not to mention that it's not as though Sidious had eight thousand Sith Lords on hand to aid him in any sort of ritual to replicate Vitiate's effort.
But if sheer speed of the attack is the standard for success, then Nihilus outstrips Vitiate and Sidious by far. He drained a world by uttering a word, did he not?