I also have this speed problem...but often it occurs in everyday speech as well. I sometimes get the words in a sentence in the wrong order; my husband is accustomed to this now and can rearrange or fill in as necessary. Also, when I talk quickly, my enunciation goes down the drain...both my dad and my friends who are not native English speakers find this difficult to understand! (I don't blame them - I dislike it myself - but it's so hard to control!)