Performance Issues when having some Activity Publisher Templates that can regenerate a huge amount of activity messages

I'm currently working on my Summer of Code project and the Activity module has a central role in it, you can read more about it on the link I posted above.

Every time one loads the Activity Publisher Templates, Activity requests for each module/hook combo if it can actually regenerate Activity. It does that by actually calling activity_batch_load($aid) which first checks if the right callbacks are in place and then actually calls the $info->list_callback callback to check if it's not empty.

You can imagine the amount of power this requires if you have around 12 Publisher Templates and somewhat 100 000's possible Activity messages that could be regenerated (like on drupal.org).

Solution #1: quick, dirty but efficient
Only check on the Activity Publisher Templates page if the right callbacks are in place, if so, show the link. The check if Activity can be regenerated for the specific hook will the occur when we're actually trying it out.

It's not user-friendly, but it works.

Solution #2: stable, but requires API changes
Make it possible to define which hooks support regeneration in the API and determine to show the regeneration link that way.