I mean while I'd agree that OP obviously is out of their expertise here (to put it lightly), pretending it's not the game is also quite disingenuous...

World save stuttering is known.
The fact that each terrain modification is stored for some reason even when the end result is the same is a big can of worms.
Multiplayer uses a pretty weird system that makes it so when you have one person with a bad connection everyone is in trouble.
Texture rendering and pop-in can get problematic if you overdo it with too many objects.

So yes the game runs well if you don't play too long, don't build too much, and don't play with too many people.
What that "too much/long" is will obviously depend on you rig and connection.

Seen some hilarious desynch issues with bosses flat out not appearing for people or multiple instances being spawned. The most funny recent thing is that one person got data saying that the terrain was still up there while it was already dug down, resulting in one person floating in the air standing on "firm indestructible ground".

So yes the game will mostly run fine until it doesn't, and then it really runs like crap.

@OP If it runs like crap to begin with, that's most definitely on your end though. I'll give the game that: when it works it does work.