i simply know is conditional tag have good performance inside a large scaly website ?

((in_array('vlc2' , get_terms( 'VLC Player', array('fields' => 'names'))) 
AND 'softwares' == get_post_type()))

You real question is hard to answer, generally, you should look at:

  • What size may be the array vlc2?
  • get_terms will query to database, are you able to avoid that?
  • get_publish_type() Retrieve the publish kind of the present publish or of the given publish. this ought to be ok.