Surely you don't want to use over 400 plugins at the same time. Having them imported adds a check box, per plugin to the DSP window. With more than maybe 15 of those, it's going to get very cumbersome and very ugly.
What are you trying to achieve? If you just want to play, import them 5 to 10 at a time and play with them. When you find you like one, keep it. When you don't, remove it.
Or play with those plugins in another software that allows you to have large banks and libraries of plugins set up. Figure out which ones you like and import just those into MC. For most playback needs, MC has a very complete set of tools already included in DSP Studio. I think most plugins are designed for studio work and not just playback.
Brian.