Whatsapp messages restore
It happened to me also, I guess it's a Whatsapp backup and restore bug, I tried to upload my backup to Google drive which is 600 MB in size and it took more than 12 hours on 1 MB/s network. I can confirm this bug was not present in previous versions, so only thing we can do is wait for Whatsapp developers to fix this annoying bug or going back to previous builds where the bug was not present.
Hope you find this useful.