VPN killing my connection on PfSense

I'm in Germany but wanted to watch uk tv on 4OD etc. So I set up OpenVPN on my pfsense router as per PIA's instructions with a few modifications but when I start the service my internet slows so bad most sites time out. The VPN is working as I can watch 4OD programs but it is so slow. 

What have I done wrong?

https://www.privateinternetaccess.com/pages/client-support/#pfsense_openvpn

 

What hardware are you using? En/decryption requires quite a lot of resources from a "standard" router, such as an alix for example.

It would depend on how many bits the encryption is. I run my VPN Server on my Pfsense Box with 256 Bit AES encrytpion. I'm using a Intel Pentium 4 running at 3.2 Ghz. 

Aye, but embedded chips found in routers aren't really up for the task.

This may be the problem then as it's a 600Mhz Celeron in my Proventia MX1004 however it never goes above 45% when the VPN is active. For the time being I'm installing the vpn on the computers and laptops on the network. Until I can figure out what it is I'll have to live with this solution but I'd rather have it on the router.