is a restart really slow as well?
try starting PC with no peripherals attached and see if it helps. No external drives, no extra USB. It could be the PC is waiting on a device to answer
Is File explorer slow to react?
Do you have an ssd or hdd? Might want to run hdtune on drive and check its health tab
go into safe mode and see if its same
at screen before login, where you click a button to bring up login box, click the power button in bottom right of screen
press and hold shift while clicking restart
this should load a blue menu
choose troubleshoot
choose advanced
choose start up options
hit the restart button
choose a safe mode (it doesn't matter which) by using number associated with it.
PC will restart and load safe mode
Is it same or normal? If its normal, problem could be a start up program
you can try setting PC to do a clean boot on restart - https://support.microsoft.com/en-au/help/929135/how-to-perform-a-clean-boot-in-windows, should be able to do that from safe mode