Difficult to say but I would start to suspend other apps one by one and see if there was any change, you said you don't use an antivirus but check windows defender, stop using the Cleaner you mentioned earlier, next I would go into resource manager and look at the top exe cpu usage files and suspend any you don't need one by one. I've actually suspended the top 9, I don't use them and so I don't need them running constantly, stuff like cortana, skype, yourphone, winappstore.