Just a little story. Picked up a nasty bit of Mackeeper adware. A quick but of reading pointed me to Malwarebytes and I was fixed in, literally, 30 seconds. Absolutely fabulous. My Mac is 5 years old and I've never done a clean instal and never a malware scan. I had 6 bits! It's possible I picked them all up at the same time, wherever I picked up the Mackeeper one, but maybe not. Maybe they've been there for years. Needless to say, Safari is much snappier!