What are your export settings? How big is the page? What does it look like in print?
On screen, sloped lines are always rendered as stairsteps since screen pixels are square and either on or off. You cannot have part of a pixel one color and part of the same pixel another color. If you outlined the type you lost the hinting (anti-aliasing) that was built into the type to help disguise this. Printers have par higher resolution than computer screens, so the stepping is distributed in smaller chunks and is less obvious.
Acrobat Preferences>Page Display>Smooth Line