On a site I run we have a facility to send email alerts of updates. Due to the popularity of the site and the feature, in some cases a single update may require sending anywhere betwen 30 to 300 alerts. Each of these alerts have an individual 'reset' link to ensure they don't get spammed with updates (ie: forum topic replies).
So needless to say, on the more popular updates the page will slow down.
How would you recommend handling large numbers of email alerts to ensure that they don't affect the page load when an update is posted?
I would schedule the updates from the foreground task ("when the page loads") into a file or database, and process them with a cron task to take this operation into the background.
I doubt it's really important enough (or breaks often enough) that you would actually confirm that all updates were successfully sent, but it's possible to provide such a notification as well.