The EOT file for Internet Explorer is always loaded first and has to be
without the format attribute.
The other font formats are specified in a comma-separated list and are hid
from Internet Explorer by the introductory local attribute. The SVG
specification contains an additional hash tag as a unique identification
number. This is necessary as SVG files may contain several fonts. However,
the @font-face generator takes care of the identification number and its
embedding into the CSS code by automatically.
Loading Time Increases with Amount of Fonts
By means of the above-mentioned options, file sizes of web fonts can be
reduced to approximately 30 to 60 kilobytes. Larger font files or too many
fonts on one web page can slow down loading of the page, especially on
mobile devices.
Weird Interim Solution in Firefox
Most browsers won՚t show any text before all web fonts are imported.
Firefox, however, displays the text using a system font and renders the text
again, when the embedded web fonts are completely loaded. This
technique results in a „flash of unstyled text“ that sometimes leads to
side-effects