The problem occurs as most templates are designed to cover a range of template position permutations, which may or may not be present in your site.  For example, your site may include a 'left' position but no 'right' position, but your template still has to account for the these.

Our approach to template efficiency is to remove any position blocks which you know you will never use.  Likewise, removing any references from the corresponding CSS file for these positions will award further performance gains.

You can often remove 50-60% of the original file size by following this simple rule.