Address Bar load times
When I open a tab I start to type immediately but as of a version or 2 back, things changed in the way the Vivaldi address bar operates.
I now have to wait for the address bar to start loading which seems to be forever and the browser wants to direct my typing to the page. This really sucks, it's not a change for the better of you want to attract power users.
This is driving me back to Chrome, I can not tell you how annoying this waste of time is.