This mod causes my game to lag when scanning a new surface. It also will stutter every few seconds when I land on a partially revealed surface. I checked show-time-usage and the numbers are pretty high. Once I fully explored the entire surface I was on the game performance went back to normal.

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That's pretty much expected, I'm afraid. Not only does it have to generate twice as many chunks, plus whatever overhead comes from the copying itself, but I suspect that the part of the code that waits for the echo chunks to be generated before copying them is causing a significant impact when generating a lot of chunks at once.

It miiiiiiight be possible to refactor things to get rid of that last bit of overhead, but the "twice as many chunks" part is always going to hurt compared to a proper fix on SE's end.

New version does things more asynchronously, which should cut down on the lag quit ea bit (albeit at the cost of somewhat larger save files).

And also it won't wipe out decoratives anymore, whoops. What I thought would be the default apparently was not.