Chainsaw Repair

I seen spike got the husqvarna 555 in now.

While I was reading I came across this on the 562xp and 555 comparison. What is the rev-boost that gives short periods of chain speed to the 562xp over the 555 not having it?

The Husqvarna 555 and 562 XP chainsaws boast a sleek and slender product design without sacrificing power.

    * Slimmed-down height and width of the saw chassis makes them easier to handle in almost any application
    * Distance between the front and rear handles has been optimized for efficient, comfortable operation
    * Lowered front handle with an overmold grip
    * Reduced gyro force technology
    * RevBoost (on the 562 XP) allows for acceleration in chain speed over short periods to increase efficiency during cutting, specifically in de-limbing applications