If you suspect that having too many icons on your desktop is causing your computer to perform slower, you may be right. However, it's not just the number of icons, but how they are displayed and what they represent in terms of files and folders - a lot of little things adding up to a big difference.
Limits On Capacity
Do too many icons on your desktop slow down your computer? Absolutely - too much of anything can be problematic. More specifically, whether the icons represent shortcuts, programs, files, or folders is relevant to consider as well as the display settings of your icons and folders. Additionally, the number of folders on your Windows desktop and the degree of customization of your icons can have an impact. The number of icons in your taskbar can indicate your system is launching too many programs at startup. Finally, the cause of too many icons being the result of too many installed programs can contribute to a slowing down in performance.
What's On Your Desktop?
The Windows desktop is always displayed whenever you're logged on to your PC. If it's filled with multiple rows of icons, it takes more resources to display, especially if some of the icons are image files and your system is set to display icons as thumbnails rather than the icon of the program in which the file extension is associated. You can free up your system by placing those icons in another folder and/or changing your folder options settings to always display icons instead of thumbnails.
Similarly, if you have folders on your desktop and the folder icons are set to display previews and filters as opposed to Windows "classic" folders, speed can be compromised by the desktop having to maintain that view. Placing the folder elsewhere and putting a desktop shortcut in its place is more efficient. Turning off thepreview setting in folder options is another way to prevent intermittent speed reduction.
Startup and the Taskbar
Leaving the speaker and network status icons out of the equation, any icon that doesn't represent some kind of system protection, such as a firewall or antivirus, is probably unnecessary. The presence of unneeded icons in the taskbar indicates that your system, at startup, is loading and running extraneous programs. You most likely can do without configuration utilities, downloaders, and messengers set up to load in the taskbar by default. As a general rule (all things being equal), the more icons that appear on your taskbar, the longer your system will take to start up.
It All Adds Up
Every instance mentioned here, when considered individually, might slow your computer down by only small increments. For example, using a pack of custom icons for a handful of shortcuts will not reduce your computer's speed to a crawl. It's the combination of all these instances that will have a significant effect.
A conservative approach will help in avoiding a sluggish system. Maintaining an organized desktop free of extraneous icons and gadgets, keeping taskbar items to a minimum, and uninstalling redundant or unused programs in addition to routinely performing general maintenance tasks will keep your system running smoothly.