There are two times I get this warning in-game. One is when I'm deleting furniture (manually, because the stupid restore button takes 10-20 minutes to cooldown and let you place furniture again). The other time I get it is if I switch my boots on and off really fast, repeatedly, for like a minute or two.
Suggests that it has to do with the server catching up to the client, and some kind of communication cap that has been put in place to avoid lag creating weirdness.