I just did this on my ball valve on my pump and I must say it made a huge difference. Theirs almost no resistance nowSimple Vaseline, I have used it for the o-rings on my Fluval externals for more than 2 years without any issues or a single leaky cannister which Fluvals used to be notorious for. If you check Fluvals website they suggest its use. It has been on my sump ball vales for well over a year now. You really only need the smallest amount, not enough to gunk up just enough so the ball sides easily.
^ correct
gate valves are designed for fine adjustments
ball valves are designed for quick on/off