Hi John and welcome to our forum,
There are lots of possible reasons for a computer running slowly, so we will provide a very broad approach to help you get started.
I will put links to some excellent information for you, shortly, but in the meantime:
1 do you have a complete 100% effective back up of everything that is important to you on your computer, including all your documents, photos, music work, downloaded executables, product serial keys9including the one for Windows itself), address books, important emails etc (anything that you would not to lose permanently)?
2 how often do you maintain the computer? (give it a general service and clean up?)
3 Do any operators of the computer practice "unsafe computing" on it?
4 Have you tried booting it into safe mode and seeing if it is quicker?(don't try and go on the Internet in this mode)
5 Have you tried setting up a new admin account and logging into it to see if there is improvement?
6 Have you run sfc /scannow
7 Have you run chkdsk /r
8 Have you run recently a complete anti virus scan with an up to date scanner?
9 If you want us to have a look at your computer's systems then use the free version of Speccy and post a link here:
and post a link to the url:
Have a look at the above link as it will provide a good insight.
Let us know how you get on with this and the answer to the above questions and we will advise the next steps.