Slow using Opera
I know that Duolingo doesn't support Opera, but I've got used to that browser and don't really like Chrome (which is said to be the perfect one for Duolingo).
There haven't problems until this new look. Duolingo on Opera become utterly slow, and it's continuously lagging... I had to change to Firefox :(
By the way, this new look looks very neat. And it's fast! :) (If only it had the features of the previous one...)
Can you clarify what you mean by it's slow: is the page loading slowly? Are the animations slow? Are the buttons not reacting quickly?
The main page loads where slowly, and scrolling down the tree is lagging a lot. Scrolling in the discussion also lags, but it is not as serious... The buttons seem fine.
The buttons to play sounds are not working in Opera beta 25 for Linux. Other things are just perfect, but the sounds were essential for me to learn pronunciation
I use Opera 12.16 and Duolingo is working fine. Scrolling is a little slow, but not too much. The only issues I've noticed are that sometimes pages never stop loading and the drop down box style is bugged. But nothing too serious, especially given it's an old browser.
I'm sure it works fine on Opera 20+ since they use the same engine as Chromium.