I assume Vivaldi uses the same video engine for videos as Chromium does. However, I've found it to be rather laggy and intensive. For youtube, I resolved to open all the videos with VLC. Thus, I am requesting a different video engine for Vivaldi. I don't care if it's VLC, gstreamer or whatever else is out there, but PLEASE a better engine!
I don't know if you're only having issues on Youtube, or with all videos on any website - but Youtube renders its videos in HTML5. I use this extension in Chromium based browsers to force Youtube to render videos in Flash player. I'd recommend trying to install it and seeing if it helps with performance.
I'd also recommend disabling hardware acceleration by right clicking on a Flash element > Settings > Uncheck 'Enable hardware acceleration.'
Have you Google Chrome (not Chromium) installed? it has the best flash plugins for Linux available. If Google Chrome is on your system, Vivaldi takes its flash plugin and uses it.
I had problems with flash also and installing Google Chrome and re-starting Vivaldi solved it.
Vivaldi and Google Chrome are based on the same engine, so they use the same version of Flash: it's called Pepper Flash or PPAPI. Adobe ceased development of any other kind of Flash player for Linux back in 2012 after they partnered with Google. See this announcement from Adobe.
Firefox still uses an outdated version of Flash player, so its native Linux client doesn't always work properly (or at all) with certain Flash content on the web.
You don't need to install Google Chrome on Linux in order to get PPAPI - but it is one way to do it. See this thread where someone asked how to enable Flash player in Vivaldi for Linux.
Vivaldi is built on Chromium, so it uses the same kind of Flash. Firefox and Chrome(ium) use different versions of Flash. Chromium uses PPAPI or Pepper Flash, and Adobe discontinued development of any other kind of Flash for Linux. You can download Flash here.
Or, if the correct package type for your distro isn't listed there, try looking into installing the package pepperflashplugin-nonfree from the terminal.
Assuming you're on a Debian-based distro (most likely one of the many Ubuntu children), just open the terminal and type```
$ sudo apt-get install pepperflashplugin-nonfree
**Edit:** Oh, and don't forget to restart Vivaldi after installing Flash.
Oh, I didn't know that. I just checked the repositories of my distro and there's a 'chromium-pepper-flash' package. That's great. Thanks for the info
No problem, I'm happy to help