alert overhead - potential performance issue?

[User]

I was poking around in the demo and I didn't see an option to set the default behavior of alerts for new users. I did see Home -> Options -> User Alerts where I would have expected those options but obviously they aren't there. What I mean is an option for the admin to define the default alert preferences for users, which are currently all set to ON at http://xenforo.com/community/account/alert-preferences

I wonder how much overhead these alerts are generating and whether that could over time negatively impact performance due to all these extra DB queries. For active posters there could easily be dozens if not hundreds of alerts, even thousands on a busy board that has some history. Multiply that by the number of active users. How well do alerts really scale performance wise?

I noticed that the majority of alerts were created by thread subscriptions and have made a suggestion to change the default behavior of subscriptions: Turn "Watch this thread" off by default, possibly adding a usercp setting

 

[Paul B]

Is this thread intended to just be feedback or a suggestion?

I can move it to suggestions if desired.

 

[User]

It was more feedback when I started typing it but it turned into two suggestions really.
Let's leave it here as a discussion as to whether the alerts actually create enough overhead to be something to worry about. I will create new threads in the suggestion forum with a more concise write up for each suggestion. I'll also edit the OP to focus more on the performance issue and less on the suggestions.