Help with Xserver 10.4.4 slowing to a crawl

I am hoping someone can shed some light on this problem. We are a small Art school, I have Dual 2 Gig G5 Xserver with 2 gig RAM running 10.4.4. The only things running on it are AFP and Open Directory. I am using LDAP and all user files are on the Xserver. I have 3 250 Gig drives, OS is on one drive, Faculty on another and students on the third. It seems to have gotten slower since I put 10.4.4 on it and today it slowed to a crawl to the point that I had to shut everyone down and restart, when I did I ran Applejack on it and skipped Permission repairs because I did not have time (I'll do that this weekend). it sems bette now but somethig is wrong. lately I have seen logon times in minutes not seconds, It usually happens mid day when 40 to 50 users are on. Network tests at this time show the traffic was not excessive and no problems pinging the server. What the heck is going on, has anyone seen problems with 10.4.4, should I go to 10.4.6? Thanks VUDUTU