So what is it that you want to optimize for? Speed? Memory footprint? IO?

You usually optimize something becuase there is an issue identified that you 
want to improve.

There's a famous quote by Donald Knuth:
  "The real problem is that programmers have spent far too much time worrying
   about efficiency in the wrong places and at the wrong times; premature
   optimization is the root of all evil (or at least most of it) in
   programming."

--- NiKom v2.5.0dev