A high chair carries a full day of dropped food in its hinges and folds, so the real work is cleaning it before you collapse it. Once it is clean, it is one of the lightest, easiest pieces in the house to move.
Pro tip: Run the seat pad and straps through a wash cycle before the move so the chair is ready to use the same night, not sitting in a "clean later" pile.
Watch out: Never move a high chair with the tray locked with a child in it; unload it before folding, since trays can pinch fingers when they release.