What is more expensive, Terrain:FillRegion or Terrain:WriteVoxels?

I have a for loop that fills a bunch of terrain regions to make a map. I was wondering if it would be better to just have the terrain there already, and just overwrite the voxels to make new maps, rather than deleting all the terrain and filling it again.

I suggest you fill the terrain instead of using a scri[t to create one because during the progress of map creation the game will lag pretty bad and if it's a lot of lands it will be worse. If you already have the terrain there it will be less laggy and the players won't have to hope that they won't lag out of your game.

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