Thanks again for the help. I already reduced the memory usage by splitting one layout into two (was using container layout already).
Now I've got a question about music.
For some reason, on an iPad, music only starts when touching the screen once the layout has started. This cause massive music problems in Healer Quest, and it happens when exported both with XDK and Phonegap Build. FYI there is no such music problems on android, and I think it's correct on iPhones, too (problem iPad only AFAIK, experienced on iPad Air 2 and iPad Mini 2).
To counter this, the only solution I found was to add the music into the sound folder, and here is my question : Does making this increases the memory usage even if the music is not played?
Another question : Is there any "clean" way to play music correctly on the iPad?
Never put Music into the sounds folder, it explodes the memory usage to insanity due to decompressing your music into raw wav files to store in memory to play instantly.
Music is streamed, to minimize memory usage.
The touch before playing is an issue with some browser engines on mobiles. You can bypass this by making a intro screen at the start of your game, requiring users to touch it to start the game. Think of consoles, "Press Start Button" menus.