The URL points to a post on "Dynamically changing form hierarchy". Is that the intended target?
While I have no idea what specific performance problems you are having, stepping back to Designer 7.0 or 7.1 does not seem to be the best solution. Designer engineering has gone to great lengths to support backward compatibility. Additionally, while the tooling has changed I'd be surprise if there was something you could/can do in Designer 7.x that cannot be done in Designer ES or ES2.
I am unaware of the public availability of legacy versions of Designer. If you have a Designer license you could check the Adobe licensing site or contact your sales representative for acquiring the installer through alternative means.
Steve