Have this set up on ph33r now, so have a go at it.  Needs Beer + Friday night for best impact I think.

Also have updated Obscurity, though needs a little more work due to a Server Overflow error.

From http://www.obscuritymod.com/forum.php?thread=62

I found that a while back, that a reason behind my lag was that vista/xp both update there internet connection utility to scan for any other internet sources in the area. Every 1/2minutes it scans causing a major lag spike for about around 5-10secs. Resaulting in "Server command Overflow"

I then searched in google looking for other internet connection devices/programs/utility's, i set it up and from that day havent recieved lag spikes or s.c.o since.

Another fix from http://www.tugaclan.isgreat.org/forum/viewtopic.php?f=21&t=16&sid=9470263e60ee0259388c4843242b9eb8 is:

1st - Make Sure You Are NOT Uploading Or Downloading While Playing!
2nd - Go To Options -> Game Options > Enable Console : YES
3rd - Open Console ( Normaly [ ~ ] Button on keyboard
4th - Type In Console, And Hit Enter - /cl_maxpackets 70
5th - Type In Console, And Hit Enter - /com_maxfps 160

From these, it looks like it is client side.

/edit
Kill cam of me getting killed in the Hide & Seek mod: http://www.youtube.com/watch?v=X8uQmAn9exE