(just back in from repairing some snow fencing that got blown down. Needed some Pool talk to boost my spirits.)
I was going to answer this too with the observation that that's a mighty powerful pump for that pool. I have a 22K inground and a 3/4 Superpump does fine. I was wondering if, as Al mentioned, there might be leaks, but also if the draw from that pump isn't exacerbating it.

I think that even if you had a perfectly sealed system, you'd still be running on the verge of cavitation (assuming the lines were 1-3/4" and not able to supply the pump's demand).

Is it a two speed pump? Maybe running it at a lower speed would help.

Chuck