its defenitly faster if you dont have them at all,- even more if you use movieClip containers or sprites as booth have events running even though you did not added ones yourself.

I am working atm. on a engine as well that has a similar projection like in your screenshot and render each cell with the drawing API (e.g canvas.graphics.beginBitmapFill(texture,matrix,... ); ) and since all objects get drawn per frame drawing as less cells and sprites as possible is important.
So per frame I check (screen clipping)
1.) which objects are visible in the viewport
2.) which faces of the objects are visible in the viewport (screen clipping)
after that I render them- meaning I use the drawing api to draw them.

another fast way is to use copyPixels if you use static 2d tiles . you say
transformed to the proper perspective
but even with that you could cache them as bitmaps and copyPixel them into a canvas bitmap. This is supposed to be very fast as the copyPixels command is lighting fast. Even in this scenario you would have to check wich cells to render on the screen so copyPixel them and thus finally render only what you need- no visible swapping.

I would say that with AS3 movieClips are not really that fast- that would be just like working with AS1 or AS2 - using sprites, bitmapData or the drawing API is the key to performance - a smart engine that calculates whats visible (viewport clipping, or camera clipping) makes sure that only a smal amount of the whole world needs to be rendered.

the screenshot looks promosing,- will follow this