Is the Fuji X-E1 slow ? It is not ! My Hasselblad 500 C/M is slow. And my Linhof Master Technika is even slower. Look for the photographes of the Hindenburg zeppelin disaster at Lakehearst N.J. at May 6th 1937. Mr. Becker made 15 exp. in less than 50 seconds.
The photographers shot plenty of pictures with 4 x 5 Speed Graphics. They were not whining about the speed of their cameras, They were professional photographers. The limitation of the speed is in the photo amateur's mind.