The goal of full-suspension on a 3.5" cross-country bike is different than a 5" trail bike. While, bigger hit bikes are about getting over, around, and through obstacles in cushy, comfortable fashion, a cross-country bike is about keeping the rear tire in contact with the ground propelling the bike forward while taking a little edge off the rough stuff.
The HiFi XC suspension is designed to be as efficient as possible for the performance-oriented cross-country racer. The custom-tuned Fox rear shock and rear swingarm hold up the damping to keep all the energy of each pedal stroke going straight into the ground so theres no trace of pedal bob. Still, the 90mm of suspension stays active enough to soak up anything that gets in your way.