The slow speed at which DuckDuckGo loads/responds to searches from Asia is quite apparent. I don't know if supporting IPV6 would improve this (will they?), but I see faster results from almost every search engine compared to DDG, which is unfortunate.
I used it for six months and it had some things I really liked about it, but there were some really frustrating bugs that would pop up each release. I eventually got tired of it and had to move to another browser.
It's a shame, because I like the attitude and spirit behind Vivaldi.
As someone who loves vertical tabs, I was disappointed with Vivaldi's vertical tab behavior/implementation compared to Edge and Brave. I used Vivaldi full time for half a year before deciding to revert back to Edge for work and Brave for personal.
Of course you can customize with CSS and other types of things, but I'd ideally like my browser to just work well and be designed well.
Having said that, I miss some features from Vivaldi. However, I am much happier using vertical tabs in other browsers that have that feature.