12# line is close to the practical maximum for spinning reels. Like others have said, lure weight and rod characteristics could have an effect. Also, what kind of line? Small diameter or large diameter line? What size reel? The ratio of line size to spool diameter is important, with the best line performance coming from bigger diameter spools, all other things being equal. You also want a spinning-friendly line. For example, Trilene XL would be spinning-friendly, while Trilene XT would not.