The main reason for a slow start up is the machine is doing too much-
Think about it- all the programs that you are not going to use straight away.- Take them out of the start group.
The A/V program and firewall and ad blocker etc., updating them selves.
So- go to Start and on the left side you will all the programs that are initiated at start up- Do you need them then?
If not right click on the icon and left click on 'Remove from Group'
Now download CCleaner[free] to clean up the system.
Then do a defrag.
Take a look at the software list.
We all install stuff for a look see and forget to remove it afterwards -
If you have promgrams loaded you no longer use- take 'em out.
Come back tell us how you got on