IPFW DIVERT Rules makes my VPS network very slow

First I'm sorry if my English is bad.
Today I purchased a VPS from digital ocean with FreeBSD OS and setup OpenVPN server. but after setting the IPFW firewall rules and NAT I found that divert rules makes my VPS network so slow. just 2 Mbps ..

Is anyone have problem like this? How can I solve this?

Please provide us with more information. What version of FreeBSD? How is it configured? What kind of VPS? How is the network configured? How is IPFW configured?