Well…sure… no way of reproducing this error. Works on all machines now 
(if it happens again I will post it)
(Reposting)
I have it working now as described:
=5v4Zbqn20hshttps://youtube.com/watch/mkOzWCGj5fk
With movable objects the frame-rate drops in the single digits. Using Static-meshes when I go to 20.000 objects it has a frame-rate of 30/40 (i7 / GTX 780 / 16 Gb)
and a little pauze whenever the Event fires.
Thanks for all the help !