I found the same. 30mg ruined my appetite completely and I felt like a zombie. The gains were fantastic vs. 20mg but feeling like a bag of smashed assholes the whole time just wasn't worth it. Don't even get me started on the heartburn.
20mg is definitely the sweet spot. You can keep the lethargy at bay with coffee and the gains are still very good.
Over 15mg a day superdrol is too much for me. I ran it for 20 days before Mexico and it was insane the amount of glycogen and nitrogen my muscles were holding. As an aside, it was so toxic when i tried to drink there I threw up, thus I opted to stay sober nearly the entire time