Flash Tutorial

Major improvements have been made to increase not only the speed of the player in both data parsing and animation, but the player has received a new text-rendering engine that allows it to show much sharper text.
FlashType
FlashType is a new text-rendering technology that has been included in the Flash Player 8. It uses adaptively sampled distance fields (ADFs) to improve the anti-aliasing quality of text for static, dynamic, and input text fields. This will be especially noticeable when you are dealing with small point text. These ADFs create outlines that determine glyphs in a different way than most text-rendering engines do. They can also use subpixel rendering on LCDs in much the same way that ClearType works. You should notice in the Properties Inspector several new anti-aliasing options.

But the rendering engine is not the only thing new to text in Flash. Flash now has a much better WYSIWYG for dealing with text on the stage; you can now select it with the arrow tool, and sizing handles will appear that, if used, affect the dimensions of the text field without scaling the text itself.
Also assisting the Flash player in speed is bitmap caching.
Cache as Bitmap
You can now cache movie clips and buttons as bitmaps to increase the level of performance because the Flash player actually caches a copy of the vector data into the player itself. When you set this option on a button, the player will cache all four states of the button.
To set this property manually, select a movie clip on the stage and check the Use Runtime Bitmap Caching option. This can also be set with ActionScript. In the following cases, however, even if this option is selected, it will not work:
The computer is out of memory, and the bitmap cannot allocate more.
The object you are trying to set is larger than 2,880 pixels in either height or width.
There are also new visual features of Flash that many designers will enjoy working with, as discussed in the following sections.