Flex 4 Module causes lower FPS up to 1 second after creation. Web browser influences the performance too.

Steps to reproduce - use the attached example, just get 2 images from somewhere for image1.jpg and image2.jpg so u can test. Here is a description of what the example has and what's wrong:

Actual Results:

On the left side we have image transition between 2 groups with BitmapImages. That is the fastest frame rate to compare with the image transitions on the right.

On the right we have 3 buttons options (from top to bottom):

1) clicking will load a module, use the factory.create() to make instance, add it to a group and on creation complete plays the animation. As you can see in this case the frame rate is lower by about 15 frames.
Note: Comparing the release version with the debuging one the frame rate is higher in the release version so the problem is less visible. In the debugging one I have about 57 frames for the left and about 30 frames in this scenario, which is like a half quality of the animation.

2) the second option is the same as 1) but here when I create with factory.create() the module I don't add it as element to the moduleGroup, so it is never created, which results in normal frame rate, so no problem in this case.

3) the third option is the same as the 1) but here I add 1000 ms (1 sec) delay to both animations, so they start 1 sec after the module has dispatched the creation complete event. This results in normal frame rate, so no problem again.

IMPORTANT: Browser influences this. With latest version of Firefox the problem is most visible. With IE7 I don't have any visible problem. With Chrome and Safari the fps drops with about 10 frames but is still like twice better than firefox.

Conclusion: The creation of module and it's elements, somehow causes lower framerate no matter that the creation have already been complete.

Expected Results:

Animating after module creation not to cause lower framerate.

Workaround (if any):

no workaround