What I have learnt is that every application is different. Eventually if you are "normal" with no issues with your background, the PR will come.
Unfortunately, the speed at which your application gets processed highly depends on your country of origin, the religious group of your home town, etc.....
Im in the same boat, stuck at background check, mainly because Im from lebanon. They tend to scrutinize applications from there much more harshly, as we have a bunch of criminals/terrorists running the lebanese government. I wouldn't recommend comparing processing times to other people, each application is different. Is it fair? probably not. Can you do anything about it? Also probably not. All we can do is wait.