Manipulating data in memory

Now, writing and reading files to disk takes time. Depending on the use case, it might not be what you want and can make things quite slow.

Imagine the following scenario: A lot of very small files. For each read/write, you'll have to pay an I/O tax time wise. This is not ideal when what you need is speed and efficiency.

This is why much of the heavy lifting data manipulations are done in memory.