Specifically, if you're webpage needs to download a font, you can
either display the page first, and let it's appearence suddenly
change when the font arrives, or you can use js tricks to delay
rendering of the page until everything is there... or you can
try to get clever, and have a portion of the content fade-in
when the font it needs arrives...
This other problem is particularly odd:
we're expected to find the fonts we need by the name of the font.
If you want to display some arbitrary text, you can't just
take the range of codepoints you're using, and use it to find
appropriate fonts, almost no one seems to index them that way
But do see: wikipedia Unicode_font
(On the other hand, css3 has some interesting features to
specify which fonts to use for different codepoint ranges, but
that's a different feature.)