It's chrome on steroids. I use it mostly on my laptop, with chrome exclusively for google services.

While it's trying hard to please old Opera users while at the same time moving forward and introducing new ideas, it's just not feeling like home. I like that it's making "power user" features easier to access than Chrome, that's one of the things I got used to with Opera. But overall it feels a little slower, which might be attributable to the JS user interface, or just in general that it's quite fat, being based on Blink. Especially opening up new windows feels really sluggish. There isn't many pages left on the web that do that, but you run into those every now and then. I think FF and Chrome "fix" this by just opening them as new tabs, but Vivaldi tries to restore the old feel of having those simple UI-less floating popup windows; with mediocre success.

I still use Opera 12 alongside of Vivaldi and Firefox at work just for fun, it's fine for browsing status pages, cgit and similar things on our intranet, and with those simple pages it's notably faster than anything else on the market. Navigating the history is another big offender here on FF/Chrome. Clicking back multiple times in Opera will instantly restore any previous page, there is no perceieved delay or re-layouting, which just feels "right" and so much more consistent than any modern SPA that tries to achieve the same in millions of lines of Javascript.

I could come up with a bunch more examples, but that's already more rambling than anyone wants to read I guess. :-)

Opera (presto) was snappy. In Vivaldi, there is a noticeable lag and the user interface written in Javascript simply doesn't measure up to a native one. The interface itself is rather nice, but the perception of latency ruins the overall experience, even on my PC with reasonably powerful specs.