Since the mirror only checks for posts on /r/all, this would eliminate a lot instances where the mirror function is almost guaranteed not to work (such as on an obscure/low traffic subreddit). Another option is to add an endpoint to the mirroring API where you POST a list of all links on your page, and it can return a list of all that have a mirror. This would add a good deal of traffic to the mirror, but the extension isn't used enough for that to be an issue.
Since the mirror only checks for posts on /r/all, this would eliminate a lot instances where the mirror function is almost guaranteed not to work (such as on an obscure/low traffic subreddit). Another option is to add an endpoint to the mirroring API where you POST a list of all links on your page, and it can return a list of all that have a mirror. This would add a good deal of traffic to the mirror, but the extension isn't used enough for that to be an issue.