I have noticed on my iPhone and ipad instagram seems to fill up all my memory until it is full and then it will undergo "cleaning" and restart the process. Why is it necessary to do this and is there anyway to stop this?
Why does instagram take up so much memory?
It is because photographs have a lot of data, especially with the newer iPhone and iPads with higher megapixels on the camera.
It's called "cashe." When you are using the app, it begins downloading other people's pictures and storing them on your phone so you can open them faster. However, that takes up room. Eventually, the app will realize that it's taken too much memory and will delete those saved images. You can expedite this process by ending the app rather than multitasking with it open. (Double tap the home button and hold your finger on the app for a few seconds then hit the red X.)