How to create prezis of a smaller size?

Hi,

I just created my first test prezi in the online editor. The size of the file I downloaded is over 100mb even though it is very basic: one picture (resized when uploading), a couple of shapes from Powerpoint and texts. No video or audio.

So what drives the size of a prezi file? Animation, a lot of zooming? How can I create a file of a smaller size? What should I avoid? Any difference if created in Editor or desktop?
Any tips?