Spawn chunks are always loaded. It's the one thing that has the most impact on performance in a world. I usually never build there as there's chunkloading mechanics in vanilla that are so easy to do there's absolutely no reason for me to build anything there, let alone my base.

Didn't think this was a thing and i've started playing the game way before the end was even a thing xD

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Plus (and this is just me) But you are playing hardcore, the point of building in spawn or near spawn is to be able to find your way back to your base on death without a compass or specific coords, which seems like it'd be counter intuitive in hardcore. Like there's absolutely zero reason to start building near spawn if the moment you are going to die you lose your world anyway and can't respawn. It's not like on non hardcore when you get into a deathloop at night and you are glad you built in the spawn chunk because you don't have a bed yet...