Vivaldi doesn't finish loading page until I click on a different window
I'm running Ubuntu 14.04 and often when I open a new page, Vivaldi starts loading the page I can follow the progress by looking at the counter that is running in the URL bar.
The counter often stops e.g. at 62/64 or 41/44 and Vivaldi freezes completely. I can't switch to another tab and click on any widget give no response.
Only If I click once on my desktop or on a different window and then click Vivaldi again, the counter starts running again, the page completes loading and Vivaldi is responsive again.
I'm running Vivaldi 1.5.658.56. I used to run Vivaldi 1.3 and that had the same problem.
I would test in the Ubuntu guest account and a session which uses a different window manager.
Also test with all extensions/plugins disabled.