Mc Afee real time scanning

I upgraded to the latest version today and now programs that took 5 or 10 seconds to load now take 5 or 10 minutes! If I turn off real time scanning this problem goes away. I would rather surf safe and use the real time scanning feature, but the computer is basically useless in this mode. Any ideas how to fix it? Would a downgrade to previous Mc Afee version do it? Help!!!