The generation of chunks turns out to be very slow, apparently the dimensions that are below and above are being generated and this greatly delays the generation of chunks in the current dimension. It also increases the size of the world, since chunks are generated that will never even be seen by the player.

A possible solution would be to start generating the dimension once the user is close to the edge or when he has passed it, this way it will not affect the game's performance in generating or generate more load than necessary on the server.

It would also be nice if you want to have a preview of the dimension, do it in low quality, showing a preview of what the dimension looks like without having to load it, and this preview becomes clearer if the edge of the dimension is close.

Also with these implementations perhaps they could add the possibility of modifying a world already created and converting it into a stack and that in case of uninstalling the mod, the world does not break.

Portals will only load the other side if you're near them. However, with a huge render-distance this can happen quite easily.

Also, simply "loading" a dimension normally won't slow the server down by a noticeable amount.

You can use the command /portal dimension_stack to configure the dimension stack after you created the world. Afaik, there is no known issue with a world breaking upon removal of Immersive Portals. If you encountered such a thing, please report it.

In ImmPtl, the loading radius increases as the player approaches the portal. If the player is far from portal, it will load only a small region of chunks.

I am going to make the world generation to prioritize in the player's dimension.

You can try to increase server memory size and install Lithium.

Is there any update on this? This makes dimension stacking unplayable on all versions I've tried for Forge 1.19.2. The world will generate a starting range of chunks quite quickly, upon going to the edge each new chunk takes ~10 seconds. This is tested with only vanilla dimensions, not sure what is going on here but it seems to be much slower than just rendering chunks for 3 dimensions.