|"I was putting off getting anti-virus software because sometimes I can be a moron"|
Considering that there's plenty of free anti-virus programs available, you are pretty moronic. Even Microsoft offers free AV:
As for your CPU usage problem, you didn't bother to list your system specs or at least the make/model of the CPU. Lenovo makes a LOT of different models of desktops, laptops, tablets, etc. Have you checked for overheating? It could be your CPU is throttling back to protect itself from frying.