Is it a situation, that all working for one and the same assignment, or there are various groups working independently ?
If is the first one, having in mind that the speed of the team is the speed of the slowest one, do investigate the bottleneck of that one. May be better interrelations or easing of the processes, or higher motivation, would bring the things quicker.
The Leader is that: " follow me" behavior, but also frequently visiting the rearguard and investigate their troubles.
Micro-managing from time to time, would be very fruitful and bottleneck killer approach.
all the best
Val