I recently replaced my fuel filter on my Mitsubishi Mirage (1994, 4G13, 95000Km). After having replaced it crystals (white, <2mm) had formed on both the inlet and outlet pipes. It was ~10°C at the time and with skin contact they disappeared, presumably melting. Cutting open the filter didn't reveal anything abnormal.
What are these, and would this be the reason the car doesn't run very well?