What does the performance of a hard drive affect?

Answer 1

The three most notable things that hard drive performance will effect is:

1. The start up time of your computer. As the information need to run the OS must be transferred from the hard drive to the systems RAM.
2. The start up time of programs.
   
3. If you are using almost all of your RAM space the system will use your hard drive to store information normally keep in RAM. In this case your hard drive performance will effect your entire system, but more ram will correct this problem better then a faster hard drive.
   

Answer 2

Two major factors that impacts computer performance related to the hard disk drive are how the file is/files are scattered across the hard drive (known as fragmenting) and the location on the drive. Fragmenting makes the hard drive have to scan more to get the "file in question's", and location on the hard drive is because the further out from the center of the disk the data is, the faster fetching the data will be (Statistically data saved on the outmost edge is twice as fast as data on the inside