What are the refresh requirements? i.e., does the CGI script have to execute the command to get fresh ouput on demand, or is the command something that can be run once a day or once an hour? If the latter, you can just make a cron entry that creates a static file.. something like (this example is every 2 hrs):

0 */2 * * * /usr/bin/your_cmd > /var/www/html/foo.html
[download]

If it does need to be on demand/realtime, you might want to at least consider using something like Cache::FileCache to cache the output for at least a minute or so so that users refreshing the page doesn't needlessly hammer your system. But depends entirely on how many people will look at this at a time and what resources the system command uses.

This is potentially relevant as well: CGI::Application timeout