i had some stange problems too, even if i dont have mods turned on, my smash game runs slow and stays that way, even if i have no mod files even on the 3ds, no options turned on the luma boot screen.
btw i feel this a good time to remind you guys that sea of thieves was made by rare, who also made DKC1-3 and DK64, alongside banjo kazooie and conker's bad fur day