I've had this happen once or twice, so I'm not sure if this is an actual issue with the mod, but when i loaded into my survival world, my entire game was constantly dropping frames. I had closed the game, restarted it, restarted the computer, updated the drivers for the gpu, etc... The only way I could get the lag to stop was by traveling away from my base so the game would unload it. Once I returned, it was fine, and I could load the world up without any lag. I'm not running any other mods except the Better PvP mod and Just Enough Items.

As mentioned, I'm not sure if it was just a one time thing, or if something wasn't quite working correctly, but if I encounter it again, I'll be sure to say something.

I am not experiencing this myself. Can you give us an estimate of how many contraptions are running at your base?
Does the speed at which they operate have something to do with it?
When you say “constantly dropping frames” do you mean that it gets worse the longer you stay there?

It's not too crazy, just a smaller scale potato farm and a tree farm that's a wip. Most machines run at a pretty low speed, I just have one giant windmill driving my stuff. Only things I run more quickly are a few fans which help draw dropped items to a belt. Everything normally runs fine without hiccups.

As for what I meant, I mean it would just constantly lag, down to 30-35fps. Normally I'm at 75 (75hz monitor and vsync) and for the most part I stay there. I havent had this happen again though, so I'm pretty curious why it lagged so hard at that time, and why leaving the chunk and entering it again fixed it.

1.14 has had some pretty strange stuttering problems in general. We'll try to do some profiling to see what parts of Create are the most heavy. Though I'm not sure if there's ever a 'fix' to framedrops like these.