WhatsApp beta app was updated to version 2.16.102 in Windows Store today. This updated app includes few UX tweaks and performance improvements. In the last update, image gallery was updated to become significantly faster. In this update, when you go to Gallery for image selection, instead of All Images section, it will go to Folders page.
WhatsApp beta is a closed beta, these improvements will come to public version of the app in the coming weeks.