Downloading a voice should take no more than a minute or two. They are typically around 1.5 Kilobytes in size.
Activity Monitor can be used to shut down virtually any task, but the trick is in knowing what task to shut down. Unfortunately, I have no clue what the text to speech task is called.
"All you've got to do is own up to your ignorance honestly, and you'll find people who are eager to fill your head with information" --Walt Disney
