This question doesn't seem too hard to give you a few general answers and solutions.
I'll give you a few options to upgrade, since this is most likely a hardware problem.
Maybe the hard drive is a bit old, usually when you have an old hard drive it kinda slows everything else down.
How old is your desktop?
IF it's the hard drive, I recommend getting either a new one (cheaper option) or a solid state drive (slightly more expensive)
I do although need to know what the rest of the specs are to see what we're dealing with.