Font files are not often updated, you can cache it for a looooong time.

Here are a piece of Apache configuration that adds some cache HTTP headers when a font files is sent to a client.

# Cache configuration
<IfModule mod_expires.c>

    # Activate mod
    ExpiresActive On
    # Declare fonts content-type
    AddType application/ .eot
    AddType application/x-font-ttf .ttf
    AddType application/x-font-opentype .otf
    AddType application/x-font-woff .woff
    AddType image/svg+xml .svg
    # Set cache duration
    ExpiresByType application/x-font-woff "access plus 1 years"
    ExpiresByType application/x-font-ttf "access plus 1 years"
    ExpiresByType application/ "access plus 1 years"
    ExpiresByType application/svg+xml "access plus 1 years"
    # Append "public" to header "Cache-Control"
    <IfModule mod_headers.c>
        Header append Cache-Control "public"

You want more details about HTTP Header “Cache-Control” ?? There you go: W3C documentation