To optimize is to modify and make progressive configuration of a function of a thing, technology, etc. Examples include remediation of unstable performance design, the effort to tidy the windows registry, to reduce overhead, noise, lag and other troubleshooting activities.
Web pages are optimized so that they rank highly in a Google search. Editors optimize code when they remove redundant characters and the Sysadmin when removing Spyware through to optimizing network bandwidth, setting up hardware in the best way, etc.
Programmers are often in search of the optimal method, algorithm or protocol to best achieve their goal. When users are file sharing with EMule, they would like to optimize the default settings depending on their system specs. Pareto was a philosopher who studied optimal economics states.