GJ, the difference is a rectangle is presented as a SPAN that gives Width, Height, (Linear) Fill and Transformation. There is no problem with scaling in the browser as it is a definition and not an image. Adding shapes changes this into an image and so you will see similar at 100% but zoom in and you get jaggies and blocky artefacts. also an image requires another HTTP call to the server and is a larger download that a definition.
If the Fill is an image itself or you use a Fractal Fill, or non-linear gradients then a bitmap has to be created.
Where possible use the rectangle Tool, even for Circles and Ellipses and use Linear Fills and Transparencies and shun Shadows & Feathering. If you need some of these, consider using CSS3.
@Xara - to recap, you have screwed up Fills BIG TIME in v17.0.
Acorn
Bookmarks