It's kind of hard to say. The timing is determined by how fast the renderer can render the frame. There are two main threads - application thread and renderer. The application thread prepares the scene and then waits. Scripts run in this thread, so the key thing is to finish with them sooner than the next frame is going to be prepared.
Actually, we should be able to tell how much time is there, need to add some statistics for that.
Anyway, the script code is normally fast, it's optimized at runtime by JIT, which can make it only 2-4x slower than native code (which is quite good for short scripts like that).