[ubuntu-uk] NFSv4 on new 12.04 server?

[LeeGroups]

Chaps,

I've recently upgraded my home server and moved to 12.04, but I'm having 
an issue with NFSv4, in that it's running really slowly, sub 1MB/sec 
transfer rate...

The old server (a little Viglen with an external USB hard drive) 
averaged 2.9MB/sec, which while a little slow I could live with, now 
I've upgraded the server to Asus EEE 701, I expected the performance to 
at least double, instead it's bombed.

I used the Minimal NFS How To on Ubuntu Docs, and then tried the Setting 
Up NFS How To, but no matter what I've tried it won't go any faster.
Any ideas?
Anyone else using NFSv4 successfully?

Lee