Its a 650D, I guess same size than 600D. I will try with "Fits viewer" unchecked.
Last night it did it again but with a (little) less time than than the other day: more 16/17 secondes than 20 secondes as the other night. These variation let me think of a network variation... That's why I wonder if in client mode the data transit via network (thus, dependant on network perf) even when all is in local. Is it possible? BTW I checked my setup profile configuration in Ekos: it is indeed in "local" mode.