IPsec site-to-site slow in one direction

[SpaceBass]

Hey folks,
First, I had to fall back to older hardware. I'm using one of the older red VK-T40E4 boxes (my SG-4860 died last week - awaiting an RMA replacement).

So I re-configured a site-to-site VPN. The server end is PF 2.4 on an xeon e3.
The crypto for Phase 1 and Phase 2 are both set to AES-192-CGM.

Server 10.75.1.0/24. <–-- tunnel ---> Client 10.15.1.0/24
PFsense 2.4                                        PFsense 2.3
                                  <------ this is fast
    -------> this is slow!

If I run iperf from the client side, I get results consistent with what I'd expect given the pipes in question: about 50mbs
If I run iperf from the server side (or any hosts behind that PF box) I get about 1.3mbs.

Also, if I run iperf from the server PF box itself to iperf.he.net I get a reasonable ~120mbs.

Anyone have any troubleshooting tips for this tunnel? I can go back to openvpn, but I understand it's even more CPU intensive, right? So if it's a CPU bottleneck on my VK device is there anything I can do? (watching top doesn't show anything above like 12%

[SpaceBass]

suggest we remove this from IPsec.
I'll repost in hardware - turns out my entire inbound traffic stream is limited to 1.2mbs and it has nothing to do with the VPN.