The hub's built in options for debugging like that aren't exactly extensive. Take a look in the logs menu, and you'll notice there are a couple tabs for device stats and app stats.
Those lists can give you some indication of what's occupying your hub's processing time, but that's certainly an incomplete picture of resource usage.
@thebearmay's app, hub information driver, can give you more detailed info about the hub, including free memory I believe.
