Yep I fully agree, but from my experience, that much delay seems like a page size issue more than a server overload one because speaking for myself, the expanded postlist page would take forever to display for me without compression and I don't have a real busy board, just average.
So basically, enabling compression would quickly demonstrate what the bottleneck is. If it's still loading just as slow (or gasp! even slower) afterwards then yeah, the server is being overwhelmed. Although imo, it would take a *real* busy site to cause that :-)
But I think I remember him mentioning that he does in fact have a lot of traffic, so perhaps he falls into that category