Clean up your Windows partition
When you are installing Windows on your computer, you are supposed to select a partition for the installation. It is advised that you keep this partition exclusively for the Windows installation and don’t install other programs on it. If your computer is slowing down when you open My Computer, make sure your Windows drive is not nearing its full capacity. If it is, you will need to clean it up.
Use the built-in Windows disk cleanup utility
The Windows disk cleanup utility is very useful and efficient. It will scan your selected partition for temporary files and any useless clutter before notifying you of cleaning options. You can choose to clear all the data and remove the unnecessary files.
You can repeat this step for all your other partitions as well
Defragment your hard drives
Over time, the continuous creation and deletion of files leads to an unorganized file system on your drive with misplaced file bits and data. This can lead to delayed read times and essentially a slower computer. In order to speed up your system, you should run the disk defragmenting utility, which is also built into Windows. This should reorganize all you data and speed up your drive and computer in general.
Check your Optical Disc Drive
When you open up My Computer, your optical drive also starts reading the disc inside it and prepares to show you the results. If that disc is faulty or scratched, it will take time for the drive to read its contents, which will consequently slow down your computer. This problem will also occur when you boot the PC, if you have set the disc drive to be the first boot medium. In order to speed up your computer, remove any discs you have in the drive after using them and avoid using old, scratched discs.