I think I have find from where the problem come in my project.
Thanks about all the profiling informations.
I’m pretty new with unreal, and really noob with the network stuff.
At the begin I have learn some methods to implement the multiplayer from youtube video.
After this I have start to rebuild my solo game to a multiplayer game.
To control the characters animation and rotation and more, All need to come replicated.
To do this I need to update all my replicated variables from the character tick… because the animation bp don’t replicate if i’m not wrong.
Because i’m new and from what I have learn at the begin… I have badly implement this tick part.
At the begin I have use a custom event for the server replications and one custom event for the remote client. This both custom event called on my character tick cause my lag problem and is my noob error 
All my characters animation appear to updating good anyway with my error but I don’t need this both custom event, Because my variable is all replicated. I only need to check authority and add all my anim and rotation data just after this. Now all seen to work like a charm and I can run 4 instances without lag or freeze.
Sorry about my english again, and many thanks for all informations in this post thread.