No collision volume in the game, after the 3d model is imported.

[minestargate]

But every time when I create a world, I edit it with setool and save it. After entering the game, it is prompted that this is an old world file that needs to be converted. The conversion you know makes it sometimes impossible to open.
The most serious problem is that whenever I create a large spaceship with a length of 500+ cubes (more than hundreds of thousands of cubes), I find that there is no collision volume after entering the game, and the characters will pass directly through it.
How do you solve this problem without collision volume?

At the same time, I am using 1.1.8.9 at least this version does not say that the world file is old.
I calculated it with setoolbox for several hours, and calculated that there was a 10 million square stargate Atlantis, with a length and width of 1300 squares. Converted to meters is 3300m.
It took three hours to open the archive, and it crashed in 15 minutes. Everything is fine and there are 4 fps (my configuration is very poor 1050ti and 7700hq)
But the most deadly thing is that there is no collision body, you will pass directly through the block, I really can't fix it. How can there be collision bodies? Open the game with a good enough computer?
But this involves another problem, that is, this game only uses a single core.
But the strongest single-core CPU i9 9900xe does not necessarily bring it? Because I feel the upper limit of single-core performance, it is really very low, unlike the graphics card that can be combined and called together. Does a supercomputer use only one core to calculate this game? haha ~