performance problem

Hello all: We have a HP-UX B.10.01 E 9000/829/K400 8-user system. It's a multiprocessor machine (I believe it has two processors). There was 2 informix server resides on the system. We recently add another Informix server on the system. We notice that one of the server's performance has gone down dramatically (jobs used to run in minutes now runs for hours). Besides adding a new server on the system, we also increased the SHMVIRSIZE to decrease the number of allocated new shared memory segments for one of the servers on the system (not the newly added the server). We also add a new disk (2g) to the system. Well, does anybody know what we should look for this performance problem. Thanks very much in advance. You can e-mail me at johnson@holidayco.com. Thanks again!