This is quite a wide subject but generally performance tuning can be most easily performed at an app level. However, first off I would recommend using apps like vmstat, mpstat, top, etc (assuming they are running something Unix like) and check for the four common system bottlenecks, CPU utilization, physical RAM/Swap utilization, network bandwidth and disk spindle utilization time. Generally one or more of these will indicate the source of the problem (which are usually bad SQL code, badly laid out database tables on physical spindles or very inefficient Perl code in that order of likeliness). Good luck :-)