Speed Up

Flatiron is a plugin (found under utilities after installation) that simplifies the flattening process for texture baking. Its main advantages over the 3ds max standard flattening tool are a more efficient usage of texture space, real pixel based spacing between polygon clusters and creating less amounts of clusters by better unfolding. With 249,- € it is more adressed to people who are regularly doing texture baking.
From the same people comes UV Packer as an "alternative" solution for 79,- €, which only does the packing procedure. This means that you would have to use the 3ds max standard flattening tool to create the clusters first, and then you would have to apply the UV Packer modifier for a more efficient placement of the clusters. With both solutions you can optimize the the texture space usage afterwards by hand using the UVW Unwrap modifier. Keep in mind you still should only merge objects with compareable scaling to one Mesh for baking them together on one baked texture.
Both plugins are available as demo with some restrictions.