Do you have a spare HDD or something you can install Windows onto?
Go here
windowsiso.net
Grab Standard W10 ISO. You don't need a key.
Put it on a thumbdrive with this
www.microsoft.com
Once it's flashed, go into your BIOS and make sure the thumb drive is the first bootable drive....then load Windows from it on whatever HDD you swapped into the SSD spot.
Make sure the spare HHD is the only one in your system, otherwise you could nuke your main W10 install.
It should only take about 10-15 minutes to load Windows 10 onto a fresh drive. If it boots quickly, then you have a W10 issue on your main drive. DO a backup of your stuff and reinstall W10.
If it is still slow, then you have to start juggling hardware.