GURPS Power-Ups 4 pg 14 lists this as a +0% enhancement.
Pg 13 under Alternative Enhancements it is singled out as being +5% (anything less than 0 is increased to that) meaning at 1/5 value it is +1%
Although the idea of a character being able to choose, as a free action, whether things work according to the game's time or OUR REAL LIFE time is kind of strange.