Hot sorting shows many day-old posts

Me again with another observation about this instance (I hope I don't seem annoying to you 😅):

I've seen that many of the posts I see when sorting by "Hot" are (almost) a day old while on other instances these same posts aren't considered "Hot" anymore.

I keep comparing feddit.de and dataterm.digital because I want to be absolutely sure that I want this instance to be my home instance, so sorry for the multitude of questions in the last days.

I suspect that it has something to do with the difference in upvote counts in instances because this is just a smaller instance, but on the off chance it might not be the cause, what is the cause? Is that something the admin/s can set in options? Is it a bug that will be fixed in Lemmy v0.18 (although we would probably see this in other instances as well if that would be the cause I guess)?

What I also noticed is that some comments don't get pulled by this instance even though it does indeed federate with the instance of the comment author. It also takes a much longer time for new comments to appear in comparison. Is this because the hardware is maybe not keeping up and might this be another cause for the difference in "Hot" sorting?