An electronically controlled transmission could certainly do a better job with regards to keeping the most efficient gear selected for any given speed and acceleration.. (greencarcongress.com)
For example, if the car is in third gear, the other clutch already has fourth gear selected but is not active. (paultan.org)
Gearchanges are made in a few milliseconds and the next gear selected in readiness, contributing to better acceleration, economy and emissions than that of the conventional manual car. (evo.co.uk)