OK, seem to be getting to the bottom of things. Diff was holding at the same diff it was when it would freeze for many blocks, this time it did finally move unlike on the old wallet.
Seems the smaller shares that would normally update speed are being considered stale for some reason.
this was accepted by the blockchain and is now 3 confirmations. So it seems it might not have been the key, just coinciding chain derpyness.
I guess stale small shares that would normally update speed weren't counting for some reason. I've solo mined a ton of coins and never seen such long diff freezes. I had it up on one monitor keeping an eye on it for over an hour on the old wallet, 2.895M frozen which it always froze at, no other number, which makes it so odd, there should be some damned variance.
Solved it, seems if the wallet systems windows clock is even off by a few seconds it starts causing the speed in the miner not to update. Even though windows was set to autosync, one sync and now the speed is moving around normally as it mines. I bet it's a once every 24 hour fracking sync, and it got off just enough at the time I added the key to start up. Miner speed now adjusting properly, never seen a coin do this before over a normal daily clock drift.
Edit: Been a while now, zero freezing issues now ever since I gave the system clocks a smack. Off by mere seconds, but it was enough. Problem completely gone now.