Very slow start up................
The first thing to try when any Windows 10 (or 8) computer starts to play up is to restart it. This is done by clicking the Power button and choosing Restart. The computer will probably boot a lot slower than usual when you do this but subsequent ones should be a lot quicker. If that doesn't help then read on:
The Windows Event Viewer boot-performance logs can frequently identify what's causing the slow down. There's more info about it here. Make sure you avoid the pesky advertisements on that webpage though.
A quicker (though much less informative) way is to have a look at the "Startup" tab in Task Manager. Look through the list for apps that show a high "Startup Impact".