Number of data bytes accessed

It is worth considering any action that reduces the number of bytes read or written. This might be important for those procedures whose time is spent passing data around among a few processes, rather than in creating large numbers of short processes. Some filters shrink their output, others usually increase it. It always pays to put the shrinkers first when the order is irrelevant. For instance, the second of the following examples is likely to be faster because the input to sort will be much smaller:

   sort file | grep pattern
   grep pattern file | sort