Ok guys. solved. I wanted to make a shower of fire balls , or rockets..
For rocket, it was ok, but for a flame shower, i had to use sprites as the models of the entities falling from the sky.
The problem was that i could see the blackparts that were supposted to be transparent.
Veco is right, it is so laggy. The thing that makes it laggy is that you have to find a origin just under the skybox.
For each entity, it slows down the game and your server.