When I use SPBlurFilter in an image the FPS go down too fast ... and I am using it just in one image ... Could it be any reason ??
SPBlurFilter can be slow, it's an intensive filter (especially on older devices). The more you blur an image the more passes it must take to complete the blur. How fast it is depends on the size of the image, the blur factor and the filter resolution.
I put the image in a sprite and did flatten it and now works great.
Furthermore, if the object does not move/change, you can make use of the "cache" method. If you use that, the filter is executed only once and the result is reused.