Slow Windows Box

[techlists at phpcoderusa.com]

Hi,

This is mostly off topic given this is a Linux List.

I have two separate work areas in my house.  I have my home office which 
is doing well.  I am using my Linux Ubuntu desktop to send this email.  
My Linux machine is hardwired.  This is my main box.  I also have a Win 
10 Pro laptop that I use to make and edit YouTube videos.  My editing 
software only works on Win and MAC.  This laptop is connected via WIFI.  
No Problems.  The O/S loads reasonably fast.  My video editing software 
loads reasonably fast and the rendering process takes a bit but not too 
bad.  This is a 6 year old HP - nothing fancy and it works.

My wife's office in another spare bedroom and she has a Dell mini-tower 
Win 10 ... I want to say pro as well.

Here is where I need help. My wife's dell is very slow and has trouble 
with loading Firefox and it takes a while to load YouTube videos.  Even 
windows takes a while to load which make me think it is a local problem 
(the Dell box).

I am reaching out because I do not know how to troubleshoot this issue.

Any help much appreciated.

Keith