VPN + Wifi Tethering = Extremely Slow

I have a vpn service that I connect to on a regular basis. I want to wifi tether to two other android devices with this VPN connection. However, when I have the VPN connected and wifi tether on my G4, the clients connect at a VERY slow rate (>1 kb/s). I can't even pull up a Google in Chrome because it's so slow.

I have seen on the interwebs that I need to run some iptables commands like so...

Code:

---

iptables -t filter -F FORWARD
iptables -t nat -F POSTROUTING
iptables -t filter -A FORWARD -j ACCEPT
iptables -t nat -A POSTROUTING -j MASQUERADE

---

But this has no effect. I think these procedures might be a little outdated since we are on 5.1. Does anyone know of a VPN+Tether procedure that works on our G4's?