Here are some specific things can you do to improve performance:
• You can make sure that the system has enough memory. As we will see below, memory size has a major influence on performance. Memory is so inexpensive these days that you can usually afford to load every performance-sensitive machine to the gills.
• You can correct problems of usage, both those caused by users (too many jobs run at once, inefficient programming practices, jobs run at excessive priority, and large jobs run at inappropriate times of day) and those caused by the system (quotas, CPU accounting, unwanted daemons).
• For cases in which you are using UNIX as a web server or some other type of network application server, ...