Many graphics and plotting programs do not take into account that people might want to send their output over the internet instead of to a local printer. These programs produce output files which can be orders of magnitude bigger than necessary.
For example, many data-plotting programs use unnecessarily long PostScript commands when plotting a point or line. If there are large numbers of data points, then this can add hundreds of kilobytes to the file size. For figures produced from programs like this, it is more efficient to use a bitmap to describe the entire image.
Note:
If you have eps figures, which have been flagged by the arXiv
system as inefficient, one of the first things you should consider is to use
pdflatex
instead of latex.
pdflatex allows to directly include .jpg,
.png, and .pdf figures and frequently these
figure formats are the original figure formats and for technical reasons
having to do with image compression and encoding they are likely a better
choice than .eps. Also, simple conversion
of EPS figures to PDF figures often results
in drastic reductions in file size.
The following pages explain how to optimize figures for file size so that they are easier for your readers to download: