Introduction

  A bad idea:
        Tweaking the kernel variables to optimize the system.

 Why?
        Modern kernels are pre-tuned to achieve reasonable
       performance under a variety of  load conditions.

 Basic rules for good performance:

        Don't overload your systems or your network.
          100% usage will delay processes and consume a sizeable
          fraction of the resources themselves.
     Don't squander available performance on unnecessary feature
           (quota, CPU accounting) 
     Using scripts and cron