This is not an exploit but it really helped me speed up my xp/hour so I thought I'd share it.
If more than 1 event is up in a zone ONLY DO ENOUGH DMG TO GET GOLD then leave and go to the another event or go trigger a new event yourself and keep moving. You do not have to be there at completion, and many times I've got gold from 15-30 seconds of dps on a 10 minute fight timer - then I move on to the next one. This ain't WoW or D3, you don't have to be in range or there at completion to get quest xp/rewards. And you can get bronze (70% gold xp) with only a few seconds of dps if you're really pressed for time or there are 3+ events up.
This works best for events with very small numbers of mobs where you will not miss the accumulated mob xp you would have gotten by sticking around. If the event has A TON of mobs/waves it will be better to stick around and gather up the mob xp as well as event xp.
This really sped up my xp/hour once I started doing this. Play with it to find the sweet spot to do just enough DPS to get gold then bail. Hope that helps!