I'm making some flash banners for a client, and our designer has used two custom fonts. The SWF needs to be 40k or less, so bandwidth is important.
The text is classic and static. I didn't really put much thought into how the SWFs compress fonts, but I guess if the user does not have the custom font installed, it will replace it with something they do. Of course, I need the font to display.
In some cases, depending on how many characters there are, I've kept the file size down and had the font look correct by using PNG images of the font or by using "Break apart" in Flash (both which increase the file size compared to just a font). Embedding the font, from my experience, increases the file size the most compared to my two workaround methods.
Are there any other methods available? I don't have much of an idea of what happens when you don't embed a font in flash, so my question really is... what happens?
When you don't embed a font it won't display when someone doesn't have it installed - but you don't need to embed a font when you only use static textfields. Flash will embedd the glyphs which you used into swf.
Set 'generate size report' in publish settings to see exactly how much the fonts you've used weigh and try different methods (breaking apart, bitmaps for small text to see what you can get). Also, fonts differ in size, so sometimes if it's possible you can find a lighter one to use. One other hack is to save text (especially small size) as gif with solid background. Then use Flash bitmap quality settings to get the lowest weight while keeping the text legible, but of course it works best for small font sizes, like small disclaimers, etc.