Statistics and performance, or something...
For GIF/PNG file generation, in a perfect quality, a 50 KB book/article goes to a range between 100 KB and 300 KB of image files, depending on font used, and the --compact option, let's say.
For JPEG file generation, in a decent quality, a 50 KB book/article goes to a range between 700 KB and 3 MB of image files, depending of background/foregroung colors, font used, and the --compact option, more or less.
About speed...
Rendertext uses to render text in its correspondent series of JPEG images lots faster than files are copied to the media device via USB 2.0. So rendertext is fast, really fast rendering.
HTML rendering
Rendertext uses a simplified HTML rendering, very similar to the HTML document linearization used for accesibility checks. Is like an adapted text + images mode. So, because of this, it is more or less very fast rendering HTML, nearly as fast as rendering text.
