Mobile ram issue

I’m trying to run my product on iOS without success on devices with 1gb of ram, after a map load the app crashes. Everything works correctly on others with 2+gb.

What could I do in order to reduce the ram usage?

I have already reduced some models, textures and audio files size, I have also disabled HDR.
On iPhone 5s, for example I can’t load the second map if I start the app using the first one, while the second map works correctly if I start the game from it. iPhone 6s does not have this problem.
Thanks in advance.

Hi ReaperF:

The following link talks about: DEBUGGING AND OPTIMIZING MEMORY Please review this page and let me know if it does not resolve your issue.