Restating the obvious:
Clean and 'polished' main and tail rotor blades will benefit lift. Clean compressor blades will benefit power.
In UK compressors should be washed after every flight as the fresh air is contaminated with salt.
Salt is sticky stuff and corrosive and is sure to degregate aerofoil performance.
Polish the blades first, clean the windows inside and out next and worry about the shine on the paintwork last.