Yeah to echo everyone else it's not Windows 10 - it's the Opera upgrade from 30 to 31 that overhauled the Speed Dial. As I've posted in previous threads the new Speed Dial is pretty much a disaster that has received a storm of negative feedback so here's what I did to remedy the issue for now:
Uninstalled Opera 31 and reinstalled Opera 30 to revert back to the sleek old Speed Dial (remember to disable the Auto Update)
Held out hope that the wave of negative feedback will eventually encourage the Opera team to resolve the Speed Dial issue for Opera 32.
Hopefully Opera 32 (or even 33) will at least fix the Speed Dial somehow by either reverting back to the old version or just coming up with a new, clean and modern look. The problem with the new Speed Dial isn't just that it's visually displeasing - it's slow as hell in terms of performance too.
So hopefully the team will take the negative comments on board and sort out the Speed Dial for the next version. There has been a lot of Opera abandonment recently but it has been my browser for so long I'm sticking with it for now. New versions of Opera will see improvements so I'm just going to keep using 30 until either 32 or 33.
Hope this helps!