** If you think this needs to be a bug report instead, please let me know **
Very strange issue here: dragging parts, models, anything across a very specific part of the workspace causes horrendous lag, to the point I’m afraid to move things lest I trigger this issue.
I’ve suddenly started experiencing this too, i think only after duplicating a Dummy that had a humanoid inside but deleting it doesn’t seem to do anything. There isn’t much coverage of this issue at all, have you fixed your problem?
From other posts ive read, any humanoid body part left behind somewhere will cause considerable lag as mentioned… if you imported this dummy from somewhere i would check the entire workspace for parts left behind (meaning the dummy you imported had additional parts that didnt delete when you deleted the dummy).
It could be physically located anywhere so a filter through the explorer is your best method of detection.