Have MacKeeper installed...
Get rid of it. Follow the instructions here:
Uninstalling MacKeeper 2012
If you have used MacKeeper to encrypt any data, unencrypt it now. If you remove MacKeeper without unencrypting your data first, you will not be able to access it later. This only applies to data encrypted with MacKeeper, and not data encrypted using Mac OS built-in encryption services or using any other program.
Once that is done, you can follow MacKeeper’s uninstall instructions here:
These instructions promise that they will remove all MacKeeper’s associated files (see the note ‘Important’ at the bottom of their page). However, you may wish to do Step 4 in the procedure below for earlier versions of MacKeeper to check MacKeeper does not have access to your Keychain.
Once MacKrapper is completely eradicated the cause of your slowdowns can be diagnosed.