FPS droped in every half minute

My PC has GTX980m, 16GB ram, WINDOWS 10 professional edition and I7-6820HK, and I have turned the effects downf my game into the lowest rate. In normal, it does has 50-80FPS, however the FPS drops into less than 10 nearly every half minnute, and I cannot ride horse or even walk in a normal way because of the lag.

I found that though my PC has 16GB of RAM, in Windows taskmanager no more than 50% RAM was used when this game running. I wonder if it has relationship with this problem.

I bought and download this game from Steam. And I have palyed a bunch of video games without this problem.

Is there any solution for this problem? I got the same issue here.
Have GTX 1060, 32GB RAM and I7-770HQ

Maybe set a larger pagefile? (Wild, blind stab in the dark!)

Anychance of having a resource monitor/tool open to see if something in the background is pinging the system on a regular basis… (sometimes moght show a big hit on disc usage or cpu etc).

I know KCD now shuts down all background tasks on startup (certainly all the monitoring tools I have up, although - come to think of it- might be because they are on a second screen; I dont tab out now because of the borderless/fullscreen/reset settings glitch)…

Suppose you could use logitech arx or some sort of remote tablet/phone monitoring software to see system usage whilst gaming)

The pagefile thing isnt likely a thing… it would require constant character movement into new areas to consistantly have the system hiccup.
If it happens even standing still… you know its probavly out of the game.
(Unless the game runs an AI pass every thirty seconds that is causing a massive CPU bottleneck)