Crossfire is not filler and not boring.
It's a
brilliant episode. An
outstanding character study of Odo and his inner torment caused by loving Kira.
A riveting performance by RA, as always. Crossfire is one of DS9's best (which is one of a very high number, as DS9 has a great many amazing episodes). It's very much like "The Wire", only focussed on Odo instead of Garak.
Crossfire is probably the
only 'love interest of the week' story in Trek that
actually works and
gets it right, because it builds upon the Odo/Kira unrequited love dynamic that has been in development for
years. Something none of the other Trek 'love interest of the week' stories do - they introduce a character for a first time 5 minutes in, the character 'in love' with a main character by 20 minutes in, and 'dead or gone away' by 42 minutes in

, which is why they are always hokey and unbelievable. Even DS9 has crap episodes like that, which
are filler garbage (ie: Meridian, Chrysalis). Crossire does not compare, it's in a whole 'nother stratosphere.