To maximize your time, do 1, 2 and 3 first:
1. Studio Tour
2. Revenge of the Mummy
3. Jurassic Park
4. [Backdraft and/or Special Effects Stage, if interested]
5. Anything else on the Upper Lot that interests you.
I wouldnt panic. Honestly I got bored with it after riding jurassic park, and the mummy. The Shrek 4d show was good, I thought the backlot was boring (not interested in seeing the outside of a building where they film such and such) which just to me boggled why people say it's so good. It was mainly beige buildings. They did have a few special effects on the rides but nothing great jmho on the backlot tour please no flames. I just found they offered very little than I expected, and the mummy and jurassic are basicly the only good rides there.
Plenty of time to see many attractions, shop a little, eat some and take photos. I don't think you can do it all, but we were ready to go after 4 hours. We enjoyed the Backlot Tour, and some other attractions.