Premature optimization

I read in the zziplib docs that a conditional call is ten times slower
than an uncoditional one. Is it true?
In src/document/html/parser/parse.c (start_element, end_element)
there are:
if (ei->open) ei->open()
and
if (ei->close) ei->close()

Wouldn't be ELinks faster and simpler if all (close and open) functions
be defined?
-- 
Witek