Although GPU Render Mode is quite fast, one downside to using it is that scale-9 movieClips will not work properly.
Luckily, this is easily solved by using a Bitmap and a Command created by Grant Skinner. Check here for details:
- Enable 9-Slice on your MovieClip
- Import a bitmap to the stage (make sure it’s set to lossless and smoothing=true)
- Select bitmap, and Command > Run Command
- Select “BitmapSlice9.jsfl”
I usually just keep a copy of this script in my /assets directory. Takes only about 10 seconds to slice a bitmap, and making changes is a breeze too.