All websites except this one are turning up huge fonts (I'm on AOL.). My speed has slowed considerably. Is this a warning sign of some kind of virus?

Probably not. I don't know what browser you are using, but look for a "text size" setting somewhere. On Internet Explorer, it's under the "View" menu. I often accidentally change this because if you hold ctrl and scroll a wheel mouse, it changes the text size. Hopefully that will do it for you.