I started using MacKeeper (Version 1.9) to optimize and for anti-virus.
I'm with joemike on MacKeeper. Get rid of it as soon as you can....and I'm willing to bet you'll see an improvement in your performance. I made the mistake of installing it a few years ago and found it really crippled performance. Then, when I wanted to get rid of it, I had a real challenge.
Since then I avoid anything like Mackeeper, MacCleaner, or any other of these types of software.
.....was hoping for a tip on a better optimizer/antivirus app.
So far as an antivirus program is concerned, I've tried a few and found that generally I couldn't let them run continuously because of the diminished performance. Sophos was a good example.
However, I have started using Avast and letting it run continuously. It seems to be just fine. As well, it's free and seems to be well-regarded. You can find reviews
here and
here.