I get a dip in my FPS I think whenever I'm around the chunks of a mineshaft. I can tell it's a mineshaft from the subtitles in my corner. Earlier in the world, I had made a camp over one and had the same FPS drops, I moved to another location (in the screenshot) that turned out to have another mineshaft far from the first and the same issue occurs. It does not go lower or higher than exactly 30 and it started happening on version 1.14.4 on Optifine and Vanilla every 10 minutes.

I do have Java updated and all other drivers up to date as well.