Why is rendering PostScript much slower than rendering PDF?

Question

I always thought that PDFs and PostScript files are quite similar, even though PostScript is a turing complete language.

Is there a reason PostScript is a lot slower when rendering (tried with evince on Ubuntu) than PDF or are the reader just a lot less optimized?

Answer 1

I've no way to currently check if my assumption is correct -- but here it goes anyway:

I suspect that evince cannot directly render and display PostScript on screen. Maybe it can only do so for PDF. So it may use a trick for PostScript files: behind you back it converts them to a temporary PDF file and display that one instead.

Try to install the (very old-fashioned) gv PostScript viewer on Ubuntu:

 sudo apt-get install gv

and then

 gv /path/to/PostScript.ps

and see if it is any faster. (gv also uses PostScript for rendering, but doesn't convert to PDF.) Or you use Ghostscript directly

 gs /path/to/PostScript.ps

But don't forget one thing: exactly because PostScript is a programming language, you can design PostScript files which are rather short in Bytes, but make the interpreter go through a loop with thousands of iterations (for example to compute + render a fractal) before it displays the file content on screen.

PDF doesn't have 'loops' and computations like that...