Tempest's sarcastic quips and constant posting of Googled Palpatine JPEG images are no match for the furnace heart of the chosen one. He fears, realizes, and knew that Palpatine's vision of Anakin's defeat on Mustafar- is the death knell to a character that Lucas devised would've crushed Sidious underfoot like the wrinkly saggy caterpillar he is. Vader is the true portrait of a tragic hero from his doomed genesis as fatefully destined to die for the galaxy, to his telekinetic abilities that make hurling Senate pods at a midget look like a casual pool game for Vader. Vader would absolutely dominate Sidious in a duel, WAIT he'd absolutely wreck Sheev so bad that he'd need Yoda's cane for his other arm. You saw how he hurled him down that mine shaft? Well, sir Vader was planning to elbow drop him, piledrive him, and make him scream for his daddy Cosinga if it wasn't for his idiot son getting tortured by lightning.
Most people don't realize that Vader isn't really slow, he just would move faster than Sidious even with his mechanical legs because his furnace heart pumps liquid fire into every muscle fiber of the remnant of his limbs. Sidious cowers in fear to the sight of cloaked and armored Vader