Knowing about algorithms and the way they work will definitely help you when you have to manipulate lots of data. Additionally, if you choose to use the wrong algorithm for a given job, you might slow down the entire process and make your software unusable.
Traditional Unix command-line utilities such as awk(1), sed(1), vi(1), tar(1), and cp(1) are great examples of how good algorithms can help, and these utilities can work with files that are much bigger than the memory of a machine. This was extremely important in the early Unix days because the total amount of RAM on a Unix machine then was about 64K or even less!
