Very Slow Animation ( fps) when array mofiier is not applied

I am facing an issue with very slow animation with array modifier.
I need to create a array of bolts on a circular surface. To do so I use a bolt, apply an array modifier to it and added an empty as offset object rotated by 25 degrees. I got the result I expect. But when a try to rotate the object, my screen is displaying only 8 fps instead of the 24 I setup. If I apply the array modifier, the speed become normal. But I don’t want to do that in order to control my file size and I hope rendering time.
Can anyone help please .