As soon as your computer finishes booting up, run Task Manager and monitor the processes to see if one (or more) are using excessive CPU time for those 1st few minutes.
To run Task Manager,
Right-click on the Task Bar at the bottom of the screen (on most systems) and select "Task Manager" from the context menu.
Select the "Processes" tab on Task Manager and click the "Show processes from all users" button at the bottom of the page.
If the "CPU" and "User Name" columns are not showing, click the "View" menu and click on "Select Columns..." and then select to show the "CPU" and "User Name" columns.
Click the "CPU" column header to sort the list in CPU percentage of use. (Each time you click a column header it will reverse the sort... 'highest to lowest' or 'lowest to highest'... get it in the CPU 'highest to lowest' sort order.) You may have to scroll the list to the top to see the processes that are using the most CPU time.
In a quiescent system the top "Image Name" will be "System Idle Process" at usually around 95%. There will then be a few other processes that will randomly be 2nd or 3rd, etc. in the list at 1% to 3%.
On one of my PCs, I get the process, "svchost" for User Name, "NETWORK SERVICE" running at 30% to 35% for 3 to 10 minutes at boot-up before any network activity can take place. I can run other programs (though sometimes sluggishly) but if they require access to the internet, they will hang until that "svchost/NETWORK SERVICE" process completes.
"svchost" is a major part of Windows, handling various tasks, like the mouse, keyboard, display, program scheduling, etc. and thus there will be many instances of it under various User Names (SYSTEM, LOCAL SERVICE, NETWORK SERVICE, and your log-in ID... and multiples of those, too).
Being a reckless sort, I have terminated that process (right click and select "End Process" and/or "End Process Tree") and found that "USUALLY" that can cure the problem, but I have to terminate it 3 times in a row (it comes back each time) before I can get it to stay away or at least let go of the network connection so other programs can use it.
I have found that I have to let it run for at least a little while or not much will actually "work" on the Internet after I get it killed! My understanding is that it is establishing my "location" and has to complete that before other things will work properly, but it seems to get hung and tie up the Network Adapter after it actually accomplishes that and so nothing else can access the Internet until it gets done, or I kill it.
NOTE: Doing this sort of thing is NOT RECOMMENDED to those that are faint of heart, as it is somewhat like playing Russian Roulette with a random number of bullets in the gun... and no way to know which way it is aimed! Yes, I have shot myself in the foot (or worse) many times,

but I am willing to accept the consequences of doing dumb things like that on MY system. I have never had something so bad happen that a simple reboot did not get things back to the way they were! But I would be remiss if I didn't give you that stern warning about playing with guns or your computer operating system! Kill the 'wrong' instance of "svchost" and your mouse may stop working, or the keyboard, or "???" until you reboot. It is possible that you could get something really in a tizzy that may take some hard work to undo. As the car manufacturers say, "Your mileage may vary!"
If you determine that there is nothing causing your present problem outside of SightHound, then run SightHound and watch the SH "Agents" to see how they behave at start-up.
Report back here what you find. Maybe you will discover what is wrong with my system and I can get it fixed!
Note, I don't work for SightHound, I am just a happy user.