I remember a topic with a local storage issue. A particular site was the culprit.

This is exactly the issue I have with one of the large Swedish news sites. If I go to www.dn.se, Opera (28.0.1750.48 atm.) keeps writing to local storage over and over and over. I cannot see any similar behavior in Firefox.

Probably the same issue as this:
http://forums.opera.com/topic/5740/takes-a-hole-year-to-load-a-new-tab

I did some monitoring, and there is tons of file and registry reading when a new tab is opened, so I suspect that the slower the hard drive is, the longer it takes to open a new tab.

I'm having the exact same problem. Even the Speed Dial page and the settings tabs take several seconds to appear. The browser puts 100% load on a CPU core even though nothing happens visually on the screen. I finally decided to start the sysinternals Process Monitor and had a look, and it looks like Opera among many other things is iterating through bunchloads of .dll files and every single .ttf font file, which takes almost a second. This sequence is then repeated again, which in total takes between 2 and 3 seconds. During this time, there is no network activity at all. The filtered log file is available at http://racehub.se/div/opera-newtab.pml.zip in case a developer wants to take a look.