How to rotate an image in gs

You can check-out pdfdraw from mupdf (package mupdf-tools under Debian/Debian-derivatives).

From its description:

pdfdraw will render a PDF document to image files. The supported image formats are: pgm, ppm, pam and png. Select the pages to be rendered by specifying a comma separated list of ranges and individual page numbers for example: 1,5,10-15). In no pages are specified all the pages will be rendered.

Perhaps it is faster for your use case.

For example mupdf (a PDF viewer) is really fast (and consumes very little memory) for a lot of documents I tested it with.

I decided to write a simple script to generate a tex file that includes eps file arguments (using \includegraphics[width=\columnwidth]{arg1.eps} ...). Then using latex, and dvipdf I can get a pdf file with multiple eps files on a page.