I just wanted to add another report of this issue. My Dell laptop has a 3200x1800 display and scaling is set to the (Dell recommended) 200%. Most programs display great, but in Opera checkboxes and radio buttons aren't properly scaled and just appear as tiny dots. As others have noted, it's almost impossible to tell if a checkbox is checked or empty.
Usually I just end up using another browser, but I'd love to see this addressed in Opera.
By way of an update, a few days back I deleted my Opera program folder and did a fresh install of v35...the scaling issues are now all resolved. There must have been some remnants from older versions in the install folder that were causing issues.
The fresh install also cleared up some HTML5 video problems I was having.
In any case, like @rseiler, I don't experience the Opera paralysis you described while waiting for the page-load to time out.
Opera is not supposed to be anonymizing. Your ISP may have no idea who you're talking to, but the site you're talking to still knows who you are - and anyone between Opera's server and the site could see as well, if it is not a secure site.
Which is to say, if you're in a country that limits access to certain sites then Opera may allow you to get around that (if Opera doesn't have a server in your country, as they do for China). But if a website prevents access from or limits access to certain regions they should be able to tell if you're in one of those regions.