My Lumia 435 Dual SIM enjoys 1 GB of RAM but often when I open an application - not necessarily a heavy one e.g. messaging apps, etc. - it suddenly closes the application, or within the application, it suddenly freezes and closes the application. I suspect this might be a RAM usage issue, but it is unacceptable as a single modest app does not seem to probably overload the RAM. I used to have an Android phone with similar hardware specs (Comparison of the two phones) but it didn't close the applications like this. Instead it got slow at times and prompted me to wait and had everything in control, but Windows Phone seems to be very hasty and impatient when handling apps. So, what might be the cause for such unexpected app exits?
Normally I would ask whether enough space is free on your phone; You should if possible try formatting and install apps to SD card if possible; If that doesn't work you probably need to take it to the Service Centre