Two more quick ones:
- At the moment you have to touch your finger to the screen every time a block comes into view. Could you add an option so that I can keep my finger on the screen all the time? That would be very handy in the later stages where it gets very hard to lift and drop your finger at exactly the right moment, because the time between its appearance and hitting the ground is very short.
- I carefully layed out the word 'DEFEAT' and it only scored me for 'FEAT'

I know the dictionary checking is what was giving you performance issues, but I think you should at least have six letter words. The screen is eight wide!
It's a very addictive game.