How can I limit my TO contact list?

I can no longer limit my TO contact suggestions while I'm preparing e-mails for sending.  All the possible per letter contacts pop up now, instead of just the "most often used" ones.  If, for example, I type B into the TO block, all contacts starting with B appear.  I prefer the former system, which limited per letter listings.  I rarely need to see more than one or two contacts from my list at a time.  What happened? The restricted version was much better for me.  Is there a solution?  Did I do something wrong?  I haven't changed any settings -- at least not on purpose.  Was there some sort of Hide/Show mix up?