I don't think it's a bottleneck. At least not yet. Games now just arn't multi-threaded (yet) but that will change but I still think your fine with your processer.
You overclock it? Do you do a lot of multi-tasking on computer?
No, not a bottleneck (IMO).
But, maby one day, when you have some extra cash, just bump it up to an Opty 165 and overclock the hell out of it (if your that paranoid about a bottleneck 😛)