Complex sentence: The play is dreadful and Avice is not much better, and backstage Julia compliments her even worse co-star and barely acknowledges Avis, although she promises to tell Michael about her.
Split into simpler sentences: The play is dreadful and Avice is not much better. Backstage, Julia compliments her even worse co-star and barely acknowledges Avice, although she promises to tell Michael about her.