Network Performance: Bottleneck Basics

The term bottleneck in no way refers to the architecture of the usual computer geek. Instead, computer experts coined the phrase when they discovered that the tapered shape of a Jolt Cola bottle was limiting their rate of consumption of the drink.
The term stuck and is used to this day to draw attention to the simple fact that a computer system is only the speed of its slowest components. It is the computational equivalent of the old axioms that a chain is only as strong as its weakest link.
For a simple demonstration of this concept, consider what happens when you print a word processing document on a slow printer. A word processing program reads the data from the disk and sends it to the printer. Then you sit and wait while the printer prints the document.
Would buying a faster CPU or adding more memory make document printing faster? No. The CPU is already much faster than the printer, and the computer already has enough memory to print the document. The printer itself is a bottleneck, so the only way to print a document faster is to replace the slow printer with a faster one.
Here are some other random thoughts about jams:
A computer system always has a bottleneck. For example, let’s say you decide that the bottleneck on your file server is a slow IDE hard drive, so you replace it with the fastest SCSI drive money can buy. Now, the hard disk drive is no longer a bottleneck: the disk drive can process information faster than the console card to which the disk is connected.
It didn’t really get rid of the bottleneck: I just moved it from the hard drive to the disk console. No matter what you do, your computer will always have some components that limit the overall performance of the system.
One way to reduce the impact of the bottleneck is to avoid waiting for the bottleneck. For example, print spooling allows you to avoid waiting for a slow printer. Spooling does not speed up the printer, but it does give you the freedom to do other work while the printer is down. Likewise, disk caching allows you to avoid waiting for a slow hard drive.