poor NFS performance in 5.x

[Antoine Jacoutot]

Hi :)

I upgraded two boxes to FreeBSD-5.2-BETA a week ago and I noticed that NFS 
performance is very slow compared to 4.x-RELEASE.
Before, NFS transfers were between 10 and 12 MB/s and now I don't go past 7 
MB/s.
My exports/mount settings did not change and the hardware is obviously the 
same.
Any idea where I should start looking for resolving this ?
It is important since I'm planning on upgrading some servers in the futur and 
homedir are mounted via NFS.

Thanks in advance.

Antoine