Memory problem on unity3d application

Hi guys,
I've got a big problem with my application, when I run my application on my device I can see that it uses a lot of memory. The application uses about 100 Mb of RAM but when I look for detailed information about the memory usage, it says that it stores about 800 Mb in cache; probably this is the main reason why my application lags to hell when I run it on my device (very low fps). I wonder how it is possible, I mean, I don't know where the 800 Mb comes from, I used iTween script to move my objects and NGUI to load sprites and all other elements. To reduce the memory usage i compress all my png to PVRTC 4. I follow lots of tips and tricks to optimize the application such as using 1 material for more sprites; is there anyone that know the reason for this insane memory usage?

 

First, I assume you mean it's using 1000MB, not 100MB. Second, you didn't even say what kind of device this is. Android I assume? Use the Unity Profiler to find out where it's coming from.

 

Yes, I'm using an android device.I used profiler to see the memory usage, it says that are used about 100Mb not 1000Mb. When i look on my device under cached background processes it says that it uses about 800Mb.