Firefox depends on GTK2 libs so try to run any GTK2 application.
If you get the same BIG font, try to tune up the resolution by adding
Code:
DisplaySize <width> <height>
with width and height expressed in millimeters to the ' Section "Monitor" ' in xorg.conf under /etc/X11
There exists one more way to tune by changing the default font size in
.mozilla/firefox/<nice weird string>/chrome/userCrome.css to something like the folowing
Code:
menubar, menubutton, menulist, menu,
menuitem, button, dialog, page, window {
font-size: 11px !important;
}
Modify the font-size value to suit your needs.