Your hard drive has a lot in common with your attic. You can only store so much in each. And over time they can get pretty cluttered.
Finding things in a cluttered attic can be difficult. The same is true for a hard drive. Files can be fragmented across different sections of your drive. This makes them harder call up. That means a slow computer.
You may have your files organized in tidy folders. But that doesn’t really affect the underlying file system. Defragmenting is the only way to fix this.
Windows has a built-in defragmenting tool. It works well. But it can be pretty slow. Defraggler is a better alternative. It can defrag your drive quickly. But it can also defrag specific files separately. You can be running faster in mere seconds.