How do I stop this message from appearing???

Okay so I've been having this problem for the past 3 months ever sense I've hooked my keyboard up to garrage band. When I record tracks by themselves I have no problems. However when I start to add more tracks to the recording Garage Band will stop me from what I am doing and tell me this

""This project has too many real instrument tracks to be played in real-time.

To optimize performance, see the 'Optimizing GarageBand performance' page in GarageBand Help."" Wow just wow, its getting to the point where I'll be playing my music, and start playing the other part of the song I'm making, and it just stops me and keeps showing me this stupid message. I've tried everything I've went to preference and used the highest settings, doesn't work. Tried using the lowest settings, still doesn't work, so I'm starting to run out of options here guys, you think you can help a guy out?? What should I do so this won't keep happening???