WD is a good start for loosening but it doesn’t leave enough lube behind. After the WD follow up with silicone spray or some other lubricant that will stay around.Spray it liberally with wd40. Helped a ton for me. If that doesn't work get a cable lubricator. I doubt you need a new cable.
An old thread.
Over time my 2004 hood latch cable became harder and harder to pull to the point that I worried about something breaking. I routinely lube those and other parts. Extra lube didn't help. Inspection showed that the pin had a worn flat spot. I rotated the pin 1/2 turn looser and everything went back to working properly.
My guess is getting off the flat spot was more help than was the 1/2 turn looser.
vic