Running Bustle should not deplete a battery quickly. Should you find that this is happening, here's a few things to try.
Firstly, after the usual close of all apps and reboot of iPad, we suggest removing any apps not used and clearing as much space as possible on the iPad. Though this will not fix a battery hardware issue.
Batteries on older models of iPad can need a service or replacement and we'd recommend you head to the Apple site or discuss with an Apple certified technician in your area.
Another option would be to look at doing a full backup, erase and restore. This does take time though. Again, if it's an actual battery issue it won't help. If the iPad is old, consider replacing it with a new one.