Thread is a bit old, but if anyone is having the same issues I resolved it by updating to a different email address, then change it back to the original email again and it resent the verification email
This can be some misconfigured antivirus software interfering. I have seen such behavior with older Opera, when antivirus intercepted all temporary files traffic and made it very slow; possible that similar problems can arise with newer Operas too.
Vista HDD background indexing is not that optimal either; I had it disabled on Vista. With 1GB RAM Vista struggles with file caching; background disk access (both indexing and antivirus) slows it down substantially.
Another, pure browser problem can be some extension - try private window, extensions do not run there.
Then enable or disable graphic card display acceleration (I really can't say, where exactly in Opera is option for that, but it is possible) - sometimes (old) video drivers are not 100% compatible.
I will give that a go, as well. I was hoping chucking the almost full half of my partioned HD into the almost empty half might help, too.