If a font has a lot of minute details to the shape it will take a lot of processor to render it in movement and loading in general. Loading an entire library from a font usually causes long load times, within the Embed Fonts property only include Basic Latin and Latin 1, don't need the entire scope of glyphs because it's huge and each export causes Flash to rebuild the font into its library.

I suggest using a lighter font and only sparingly use specialized fonts with details for things like titles or headings where movement is not a requirement.

Cheers.