@alexproe
We regularly make improvements across the board, so whether things have improved for you depends when you last used Vivaldi.
I recommend giving it another go and if the battery usage is still high, please report the issue on https://vivaldi.com/bugreport/. One thing you could try first is how the battery usage is with the Tracker and Ad Blocker enabled vs disabled.

Also, please tell me more about what makes managing Bookmarks in Vivaldi on iOS difficult for you. Hopefully we can recommend something to make it easier.