I'm experience the same issue, and I think what it is, is as you move around the game, it spawns in animals and monsters, and when it does this, it triggers a frame spike.

Its quite jarring and also a bit immersion breaking since you know a monster just poped somewhere closeby.

yeah, i've noticed it happen when any of my plants are done growing as well so i'm sure thats what it is. anything spawning, finishing growing will sometimes cause it. it definitely is immersion breaking and has caused me some issues in the middle of battling mobs.