Long time to import from PowerPoint?

You might want to dig into that source PPT file and see how many master pages and layouts are being implemented in the file, because it may seem like you are bringing in only a few simple slides, but if there are excessive master pages and complex layouts to translate in the sub layouts, it takes time to process that for every slide you import.  

This issue becomes compounded when you try to import chunks of slides because your Storyline file is going to contain new master pages and layouts for EVERY batch you bring in, even if layouts match slides that were brought in previously.  There's currently no way for Storyline to recognize that it's pulling from a "familiar" file.    The Master page manifest can get very long and complicated and hard to unravel.  Again I recommend cleaning things out on the PPT end, saving an intermediary file and then I guarantee your import times will dramatically increase.

This should honestly be an option within the import dialogues to let the developer decide what masters to bring in.  (no im not submitting this as a feature request, I feel like this is an issue that Articulate will have to decide is worth that level of scrutiny and control)