So, definitely not the clamp. I took the right rear brake off, took the pad off, and watched the piston go in and out. It's going slow unclamped, but only the right rear. The left rear (where the brake the hose goes to first) moves quicky and with almost no delay to the lever squeeze -- it's practically instantaneous -- and on-point throughout it's stroke. The right on the other hand has a delay on the release. I can squeeze the lever in and then drop it, and I hear the "thud" of the lever well before the piston goes back to its resting state. I cleaned it and lubed it with a silicone spray, pumped the handle several times, then wiped all down and it still goes slow. I'd say it's maybe marginally better than before. It almost seem like some kind of pressure difference or blockage on the return of the piston. Thoughts?