The regular red can of CRC silicone spray always make my cube very smooth and fast after it dries, but after a few days / couple weeks it becomes slightly gummy. It's still relatively quick, but there's an obnoxious gumminess. I've since turned to Prestone silicone spray, which works just as fast, but doesn't have the gummy after-effect.
CRC doesn't impress me, and I've been trying to find a replacement. Prestone seems like it doesn't last long; I find myself spraying in the cube more often than I feel like it should be necessary.
I'm ordering CRC's food grade silicone to see how that works out, and I'll try the Rubiks.com liquid later. I can't remember where I saw the post about the bulk rubiks.com liquid silicone... the single syringes don't seem like they're worth the money.