if its windows - the one thing i kill for sure are the so-called 'windows ornaments'
deskptop>properties>appearance>effects and kill all of them...
try it out...have all of them 'on' and minimize a window and put all of them 'off' and then minimize a window....and that is a big help when applied to anyother package as refreshing gets much quicker this way and not the windows animated way...