How can I prevent or limit CRON during SimpleTest? I have a CRON job that tops up a huge cache table. Normally, it only updates a few records. But the first time it runs in a new installation, it has to load the entire table with thousands of requests to an external API. This gives SimpleTest a big overhead for any minor test in the module.

How can I skip or limit CRON when SimpleTest creates a new installation?
I didn't find a way to know directly whether SimpleTest is running. For now, I am checking a role that the module creates for users. If there are no users of that role, I assume its SimpleTest running and limit my CRON.