the system scan goes automatically, around noon i think.. but that doesn't slow down my computer.
What slows down my computer are the updates and update installations that Mcafee does.
My computer still slows down during updates. I haven't really gotten a solution yet. But as a temporary solution, my updates are not automatic anymore and so when I know i'm going for lunch or something i manually prompt mcafee to start looking for updates and installing them. Even then, I do that not every day anymore, more like once every few days because it takes the same amount of time for Mcafee to search for updates and install them whether I do it in every day or after a few days.
No, I didn't delete any processes in task manager. But I have noticed a significant speed increase without Mcafee's updating process.
If anyone has a better solution, please let me know.