You should ideally use a fresh OS and no anti malware while mining. AV/Malwarebytes can slow down your system CPU, complain about various mining software and slow down your internet connection if it's suspicious, so I think it's best not to have an active av/am software working on your mining rig.
I was experimenting mining a CPU based coin like Yenten and Ring coin and I notice slowing down of my pc and it heats up also but when I turn off the anti virus it fixed everything I'm planning to transfer to another pc without any anti virus so I can mine steadily.