Allocate more RAM to the game, first of all, I'd say about 3-4 gigs or so.
Try this too:
-Go to the windows settings,
-press "System" then navigate to the "Power & sleep" on the left
-there will be something that says "Additional power settings"
on the right, press that and it will bring up a new window
-It will say something like: Balanced (recommanded) and High performance.
if you have balanced selected, select high performance.
-press "Change plan settings" next to the high performance button
-press "Change advanced power settings" it will bring up a new window
-Press the + box next to the "Processer power management"
-Press the + box next to the "Maximum processer state"
-Change everything in that section to 95%, I am on a laptop so it has
"On battery" and "Plugged in", if it doesn't have one of them don't worry, just make sure it's all at 95%
I had a problem with some games where my specs would run games easily but then sometimes the processer would cap at 100% and lag the game, I tried those steps and it worked for me. You can try lower than 95% but that is what worked for me.