Controller input lag after a few hours playing. Is it the controller, or the PS4?

I have spent the last hour trying to find information on my issue, but no luck. Thought I would ask here.

After a few hours of playing my controller starts to have input lag issues, which I find very strange. If the controller was on its way out, then it should have input lag issues the moment I start using it (right?). Resetting the controller or restarting the PS4 doesn't solve it. Only thing that seems to solve it, is leaving it all turned off for a while. Next time the same thing happens. Play for a few hours, then the lag kicks in.

• The controller is wired.
  
• I have done the reset (little hole on the back),
• Checked cables etc.
  
• Checked my connection (though I'm not playing an online game when the lag happens).
• Check for anything else other articles / posts have suggested to do with the controller.
• Also done database rebuild just in case.

Edit: Controller is standard dual shock, and PS4 is regular.

I don't have a second controller or can afford to just take a gamble on buying a new one. Am hoping someone here may have an idea if it is the controller or the PS4?

Thanks

Edit: Is this the wrong place to post?