I suggest you remove netcut alone with netcut defender , and see if your network speed back to normal.
the reason netcut use lots of your memory most likely cause your are cutting gateway, which cause network storm.
once you verified the network speed back to normal when not running netcut. try install netcut and NOT CUT ANYONE, NOT turn on defender. see if it back to normal?
we are a new release on going that will give more choice on how to cut and detect network nodes. stay turned.