Hello bro, I come from your future and here are the 4 main solutions for your performance issues (Real life feedbacks ! 
)
- Very Low FPS : Too much Ai processing, and too much uses of Event Ticks and too much rendered actors : Change Level of Details (LOD’s) and Distance Culling and level of textures for each actors, check if event ticks are really needed or replace it. OR just buy a complete solution for all that stuffs like this product https://www.unrealengine.com/marketplace/en-US/product/global-world-optimization-framework-pro-max-with-multiplayer.
- Sounds interrupted : Use Sound Concurrency - https://www.youtube.com/watch?v=VKoDPaT3Iew
- UE Packaging steps: There is only one full tutorial on that for beginners : https://www.youtube.com/watch?v=O2PKihXmejw
- Packaging Error: if the packaging tooks less than 2 hours , it is just an error alert already notified before in your UE Editor during the devlopment of your game ; if the packaging tooks more than 4 hours, you will probably just need to run it again for the one or two hours left before the end. Packaging error unknown issues: https://www.youtube.com/watch?v=KK5rjU-KWn8