When starting out with Scala/SBT I very quickly ran into perm gen issues followed by SBT crashing:

java.lang.OutOfMemoryError:
    PermGen space

Especially when running the console from within interactive mode.

To fix/brush this under the carpet add the following to your profile (.bashrc / .bash_profile) and source it again (run . ~/.bashrc)

export
    SBT_OPTS=-XX:MaxPermSize=256m