That's not the issue. But it can cause ALL versions of Windows to be sluggish since Explore wants to read each file to pick up a thumbnail or other data from the files in the folder you opened.

Unless you clean the files off the PC, Explorer will continue to work hard to deliver icons and information as you open folders.

Why do you need to use Explorer? Maybe a lighter weight more nimble file/folder browser will do? I often suggest Gyula's Navigator when we need to get around faster. There are others too.