"What are their reaction times?”
    “Almost impossible to chart. We estimate it at twenty milliseconds,” Mendez replied. He shook his head, then added, “I believe it’s significantly faster in combat situations when their adrenaline is pumping.”

Halo: The Fall of Reach Ch 8

    “Most importantly,” Dr. Halsey said, “the armor’s inner structure is composed of a new reactive metal liquid crystal. It is amorphous, yet fractally scales and amplifies force. In simplified terms, the armor doubles the wearer’s strength, and enhances the reaction speed of a normal human by a factor of five.”

Halo: The Fall of Reach Ch 13