I wonder if there's a ceiling effect here in that OP was already using a light butyl tube with a quality clincher tire before switching to the TPU tube.
No experience with TPU tubes personally, but I do notice a smoother ride going from light-medium weight butyl tubes to latex tubes on the same tires (Vittoria open clinchers). I didn't feel faster (confirmed by Strava) but it felt smoother and more comfortable (could be placebo, for sure).
Last edited by tFUnK; 03-22-22 at 11:53 PM.