Kind of true.
If one uses laptop with CPU that is not recent Intel 11-12Gen then it’s quite possible that even Youtube will be quite laggy playing basic 1080p@60fps videos. In Kubuntu it will work flawlessly even in 5 players simultaneously due to hardware acceleration that is not available to qubes in Qubes OS.
Other stuff is about twice slower to my estimation, that is not a lot.
Qubes OS has several advantages over GNU/Linux for average users:
- It can run applications completely offline (like in some offline vault qube). The other way to see it - you can store data offline, no application is able to send it anywhere because the whole qube is offline.
- Applications are limited in sharing files, clipboard and anything else, you can separate them better.
- Qubes OS allows the easiest way to make chains of VPNs and even Tor. It’s not possible on GNU/Linux.
Everything else is the same (except security, of course) as in GNU/Linux.
And a lot of things in Qubes OS are worse or not working at all compared to GNU/Linux (like VirtualBox).
Long story short, if you completely do not need all of these 3 advantages and you are not too much concerned about security - you do not need Qubes OS.
Otherwise, welcome aboard!