In Web development, many different bottlenecks can exist for a given website. Following are a few of the more common bottlenecks encountered:
Processor (CPU)
Memory (RAM)
Bandwidth
Storage (hard disk)
Dealing with these bottlenecks to achieve the best performance from your Web applications is by no means an easy task. As will become clear later in the discussion, relieving one bottleneck often is done at the cost of increasing bottlenecks elsewhere. For instance, almost all optimizations that use less of your processor's resources do so at the cost of additional RAM or hard disk space.
It is because of this space-time complexity (to coin a term from computer science) that optimizations must be done on a case-by-case basis and with a firm understanding of the resource utilization of the application.
When dealing specifically with PHP, developers make a number of common mistakes that lead to inefficient programs or unnecessary resource bottlenecks. Sometimes these mistakes can be nothing more than a single line of code; other times, they can be slightly more complex. Compiled in this chapter are some of the more common optimization-related mistakes made by developers and possible solutions to them.
