I know statues, and walls block movement. I know chairs don't. Do chairs slow dwarves down? What about other things? Armor stands, cabinets, etc?!
Very few buildable things in Dwarf Fortress block movement. As you witnessed yourself, Tables and chairs are casually ignored. There are two principle items that block movement (nothing slows movement, unless the dwarf is carrying something particularly heavy, like an elephant cage)
Constructions -- specifically walls. Dwarves can't go through walls, natural or constructed (duh!). Also included in this category are Flood Gates, Bars (horizontal or vertical, for their respective directions), raised bridges, and locked doors / hatches. Statues, windows, etc.
Workshops -- The specifics of which workshops block which spaces varies greatly based on the workshop itself. Do mind the jeweler's workshop, one of the few workshops to block the three leftmost squares of the workshop's 3x3 grid; more than one dwarven overseer has accidentally locked their poor jeweldwarves inside 3x3 rooms when they arrived to construct the workshop.