It sounds like there’s something else going on with your machine. I’m on a quad-core Mac Pro with 16Gb of RAM and I would say it just feels sluggish, especially compared to other apps. Meters seem to be fine on mine. Definitely not what you’re experiencing. I would have stopped it using it by now.
Do you have anything else running on that machine eating up CPU? What you’re describing sounds exactly the way Pro Tools behaves when you open a session with missing audio and it starts searching the disk to reconnect media. Still works, but in slow motion. Possible that you have something beating up your disk like that?