Ubuntu Servers :: Slow Performance On File Server (LVM/ReiserFS/SoftwareRAID)?

It stores all my important stuff, as well as some music and movies.I use a second linux box in my living room to "stream" content via NFS or SAMBA share.The streaming tends to stop several times during playback, and needs to fill up its buffer again before continuing to play.I also have some Windows XP and 7 based computers that connect to this file server.I have noticed that directory listing is VERY slow, and there is a huge lag when I want to save/read a file from/to my home directory.

This is my setup:Ubuntu Server 10.10 64 bit (I have the same problem with 32bit ubuntu)
3 RAID5 arrays with 4 hard drives eachLVM on top of the 3 raid5 arrays.The Logical Volume i use is about 6.5TB, and I use the ReiserFS file systemThis LVM has grown over the years, and has had som replaced disks. So I have used the pvmove, and extend commands a bit.I have tried using IOTop and top to check if there is not enough resources available, but that doens't seem to be the problem.I haven't been able to find out why streaming over the network stops, but I know it is the server that causes the problem.Does ReiserFS have any performance problems with large logical volumes? Would changing to EXT4 or some other FS give any performance gain?