I play off a USB passport drive and it only hangs for maybe a full second. I've not really noticed a difference between many different worlds. Fully explored worlds maybe half a second longer?

10 - 20 seconds seems a bit excessive, if you are sure about that time frame then maybe you should verify local files. Library - game - properties - local files - verify

Do you run a lot of mods? I run the game unmodded.

It's been always like that for a lot of people (myself included), hence they added a 30 second reminder before it happens so they won't get a sudden freeze when it combat or moving.

I've read that it isn't much of an issue if you haven't travelled a lot of areas hence the game doesn't really save a lot, but I'm unsure of that claim. Personal experience, sometimes it freezes me or sometimes it's just a straight up fps drop (not a complete freeze).

Originally posted by Cthulhu:

is it just me or has the auto save started to freeze the game for 10 to 20 seconds now. this started for me after the last patch.

If you put Valheim's saves(not just Valheim itself, but also its save folder) onto an SSD, your waiting time should be reduced down to 3-5 seconds.