After more observations I believe this window is the cause of a lot of the Firefox crashes.
Even if it's not, it's 100% responsible for the Firefox browser becoming unusable in the middle of turns in games past turn 15 when you have lots of men to move. Every time you do any action in the game, something gets written to the log. This log gets longer and longer and uses up more RAM storing all the events from the turn in a gigantic buffer. Eventually a single click on a unit takes more than 10 seconds to process. At this point I have to kill the browser (task manager) and restart it.
It finally dawned on me a few days ago when I started the browser fresh, went to a game and did nothing but look at vectoring by clicking on my cities. By the time I had clicked on 20 cities, the browser was literally at a crawl. Before that I always assumed it had to do with a lot of server interaction + moving units. But in this case (and in several since then) I was doing nothing but looking at production/vectoring.
So can we have a way to turn off the debug window please.
KGB