It's smallish here on the Mac running FF. Mac users have the ability to increase font display size using the key combination CMD +, which makes it easy to configure individual sites.
My very limited understanding of ms type fonts is that they use a built-in scaling agent which communicates with the display engine of either the browser or the OS. When I open TFP with Safari I get a slightly larger, crisper display than in FireFox, requiring no font size adjustment.