The short quick answer is that imported vs local items should have zero effect on your problems.
your problems are more likely tied to either world file size (too many changes to the world, too much stuff stored, etc) or bad internet connections.

Whether your get local or imported materials, the game can't tell the difference.

It may be safer if you all stay together. Each area in the world with a viking in it must be activated, and probably stored during a save. The more areas you guys have active at once, the more instability you could have at save time. This also applies to areas visited between saves: the more of them, the more it has to do. Inactive areas, like an old outpost with a campfire, will get timewarped WHEN a viking enters the area, burning all the wood at once, and then next save will update the file to reflect that it has no wood left or whatever. But if you stay away, it doesn't seem to update it.

the most likely fix for your problems is to keep the world file small and your internet connections running hot and fast.