animated texture and the FPS

I try to make an animated texture with the
node.
I used a rendertexture to do that.
Without the animated texture the scene work a 280 FPS but the FPS fall down to 50 with the animated texture. And it's only a cube.
Here is my scene
I've certainly used the false method.
thank's

I used a rendertexture to do that.
Without the animated texture the scene work a 280 FPS but the FPS fall down to 50 with the animated texture. And it's only a cube.
Here is my scene
I've certainly used the false method.
thank's
