Now it seems has been solved! (maybe through an update, I don't know...)

I'm counting up to 8-9 seconds! Before it was almost instantaneous.

(Intel Core i5 7th Gen., 8Mb RAM, Windows 10 last update)

I'm having the same issue. I don't know how does it take exactly, but it seems to me a full lifetime in comparison with other browsers like Edge and the like! Please opera guys, fix it as soon as you can. Thank you!

For me, the "light" background theme is too light (an almost-white-very-very-light gray) and the "dark" theme is too dark (a pitch-black background). So please could you implement a "medium" theme, i.e. a light theme with a medium-gray background?

Corrijo: no son solo los PDF, y tampoco es donde le sale de las pelotas. Acabo de darme cuenta de que Opera me está descargando todos los archivos en una carpeta que ha elegido el programa por su cuenta y que no tiene nada que ver con la que yo tengo seleccionada en el menú de configuración. ¿Alguien sabe alguna forma de arreglarlo, o al menos de revertir a la carpeta de descarga por defecto?

Hola a todos:
Perdón por el lenguaje, pero es tal cual lo digo. Tengo configurada una carpeta de descarga y además activada la opción de preguntar antes de descargar, Pues bueno, cuando primero abres un PDF en Opera y luego lo descargas, te lo descarga donde le da la gana y tienes que ir buscándolo por todo el equipo. Raro, ¿verdad?, pues es tal como os lo cuento, ¿Le ha pasado a alguien más?

@athlonite Today with same update I can open the Google Sites' website, but still not the Amazon Alexa's.

OK, but I'm not sure whether Opera guys monitor these forums. Do they do it?

I don't know what hidden interests can lurk behind this, but today I've found no less than 2 websites that refuse to work in Opera requiring instead every other browser to access: the Spanish Amazon Alexa setup site (https://alexa.amazon.es) and the new Google Sites design page (https://sites.google.com/new), Please Opera team, take note and fix it if you can. Thank you!

"Vivaldi is the only browser I've seen where the browser UI elements' size can be changed independently of the size of the window contents."

Firefox too, via "about:config" tweaking + an addon named "Theme Font & Size Changer", which results in a perfect UI & content custom size. It's that kind of solution I miss in Opera.