Having a large level slightly lags and jitters

I am new to UE4, and I am not quite sure how to optimize large levels for more consistent frame rate. I have a pretty big level, when I play it every 10 seconds or so it has a slight jitter, I have a pretty powerful pc, so I don’t think it’s my computer at fault. I just to be able to make an extremely large level, but without the slight jitter, I’m hoping someone can give me some optimization tips.

It’s hard to say what could be the problem without some details, but about the optimization tips:
There’s some courses in the Unreal Learning page that i think will be usefull: