levels are lagging out of nowhere

I dont really know how to describe this but basically I'll be on 360fps and then out of nowhere every 1 - 2 secs it just decides to drop to what feels like 60fps for about half a second and then goes back to 360 fps.

I dont know why this is happening, it doesnt happen often but sometimes it just likes to happen out of nowhere and it really annoys me.

for one attempt I got a really big lag spike and then it was normal again. until I paused the game for like 5 seconds and when I came back it was doing this again so can anyone help me or is this just something im stuck with?