I finally got pissed enough to dig around the exploding Firefox log files problem (see here and here). Happily, I’ve found a workaround. Find and open the browserstate.js file in your Firefox profile folder. Look for and modify the constants CLB_Application.MAX_LOG_AGE and CLB_Application.LOG_ROTATE_INTERVAL; both are specified in milliseconds. I’ve set the former to 30 minutes and the latter to 15 minutes.