iZotope Ozone 3 is the most CPU efficient audio signal mastering suite I’ve ever come across.  It has a neat GUI that looks like something off an old terminal, that nicely ties together a range of processing tools.  It has a multi-band compressor/limiter/gate, a Maximizer, a Tube or tape saturator, that can effect the defined bands with different intensities, it has a stereo imager that also can be applied to the defined bands with separate intensities.  It has an 8 band parametric Equalizer, for freeing up bandwidth by using gain staging to give your bass more breathing room, and it has scopes and analyzers to boot!  This is a nice plugin to have.

Check it out here!