memory leak

I have a decent gaming laptop. GeForce Experience itself sets everything to ultra settings, but I have done testing, and even on the lowest settings fps after 10 minute gameplay drops to 15.( 10 min runs on 60) I have all dlc, i have no cas cc, and only a few mods(mccc, collection mod by carl). To find out what's happening went to task manager as game runs, shows 78 percent memory, uses 1.2000 MB(nothing else runs in background), i don't have anything else running(processes). Everything is up to date game vice, ea, and my drivers.