Does your computer disk still have a lot of available space?

First, let's reinforce that keeping a good amount of free space is a solid first step. A full drive struggles to find space for temporary files and new data, and it can make fragmentation on traditional hard drives (HDDs) much worse. The general recommendation is to keep 10-15% of your drive free for optimal performance. However, research shows that normal, everyday use of a computer can slow it down long before it ever gets full. This is where the other factors come in.