Scheduled posts increasingly late

Hi everyone –

One of the larger wp sites I help maintain has been seeing some strange goings-on with regards to scheduled posts. Over the last 2 months we’re seeing the scheduled posts continue to slip from going live about 2 minutes late, to where it is now – at 30 minutes late (on average).

We’ve set a cron job up to hit wp-cron.php every 5 minutes, thinking that would fix it, but it hasn’t.

I know that some might request we turn off all our plugins to help track this down but unfortunately we can’t do that in the live environment where the problem is happening.

Are there any pointers or places we could look to view errors that might be occuring? Or some way to diagnose what’s happening when we try to trigger future posts?

Thank you very much!