I would not reccommend upgrading old hardware with new software like Windows 10.
It is more resource heavy than XP, Windows 7, etc.
Windows 7 is also specifically designed for PC while 10 is designed with parity in mind (meaning it is not optimized for PC, it is designed generically to run with PC, Tablets, Xbox, phones, etc)
You probably have lots of stupid unnessicary shyt running.
ctrl+alt+del to bring up task manager. In the bottom left corner it'll say processes and have a number. This is how many programs are running.
select explorer.exe from the list of processes, right click and select end process tree
then click file (at the top in the task manager which is still open)
click new task and type exporer.exe and hit enter.
what this does is it closes your desktop (explorer.exe) thereby closing all misc programs that need your desktop open to work (like adobe updaters, background stuff, basically everything manualy installed) then turns your desktop back on without turning all the extra stupid shyt back on.
if you need something that isnt running just reset your computer and all of the default stupid programs will start up again with the desktop as normal.
this does not delete anything, it just turns things off.