|Reboot simply means to restart the computer with the power off/on button.|
If you mean "factory restore" (returning it the way it was when you bought it) then what is the make and model number of your computer? This process loses everything you have added since.
What disks, if any, were provided with the computer?
Install and run MalwareBytes (free) as a first step to see if your issue is due to a virus - it often finds what AV's miss:
This only runs on demand.
If you are running more than one AV or Antispyware program permanently in the background than that can cause slow-downs. Too many other background programs can also cause this but waiting 5 minutes is a lot - hence my suspicions about a virus.
Always pop back and let us know the outcome - thanks