Software that isn't deliberately made to be malware but by it's function slows your computer/device enough to make it not worth using.
For example, BlackberryBBM Enhanced Symbols, an integrated menu that gives you a huge array of smilies and other symbols but bogs your smartphone down.
-Did Joe send you the link for the BBM Enhanced Symbols menu?
-Yeah. I uninstalled it though, it's clunkware.
-Joe should be beaten.
-Yes, yes he should.
-I'll fetch the truncheon.
-And I shall prepare the oranges. For halftime.