Google Gallery and Google Music player are both problematic.
As long as you keep the stock Google Music player it is not a battery killer.
As for Gallery... I found with over a few thousand songs with album art in mp3 tags, and a few large images for changing home screen and boot screens. My gallery cache can get over 400MB and still grow as long as I keep adding more images. It will eventually stop as long as images are not added.
Like I said, I can have gallery run without having to clean out cache, or turning off and on the app.
Unfortunately it requires rooting to use xposed and Wanam addon. Having wanam really helps with turning off Samsungs Dynamic Voltage for accurate battery charging status, and disables caching for gallery.
Google is really dropping the ball on support and proper development. All they want to do is bring out new wizbang items, rather than fix. So if anything, 4.4.x should hide Google's lack of support with Apps running on 4.2.2.
I guess I am the only one with a full months listening time of songs loaded on my SD card for both issues to show regularly.
