There is a high memory consumption when App Builder and Form Designer is used continuously for many days without navigating to any other screen like Manage Center or Work Center. This is only specific to Internet Exlorer and memory can grow beyond 1 GB for Internet Explorer process. This is a rare case as typically people save the app and navigate to other module once every few hrs. However in some rare case they might keep App Builder window open and keep using it for a while.
In IE, there is a know issue with garbage collection of its memory when iFrames are used. So even if we destroy the iFrame instance , The memory never comes down. Only way IE clears this memory is when we navigate or refresh the page.
So in case of App Builder and Form Designer, we are using iFrame multiple places and these are dynamically generated. Once they are not in use we are destroying it.
There is an article from Microsoft stating that this is know issue and they are addressing in the Edge browser.
However as noted they won’t be fixing this for Internet Explorer. Please note that the status is set to “Won’t fix”