It is my understanding that this feature is designed for someone on a dialup connection, but I'm on a 3.3mbps cable connection. Yet, Opera keeps popping a dialog on occasion, saying that I'm on a slow connection, and should consider using the Turbo feature (it is disabled in settings)
While I do find that Opera is exceptionally slow to initiate, once up, it displays pages fairly quickly, although I have seen it somewhat faster in the past.
This behavior has existed over the last couple or more installations, so I doubt that installation is a problem. If there is a problem, I think that it exists outside of the browser, but how would I check that?