I’m not aware of all details, but I understand it is possible to (ab)use guesting to farm event and dragon chests and gathering nodes.
I believe this is the reason for the major lags in chest-events because some players (ab)use guesting for farming.
Personally, I don’t care if they farm by guesting. They can farm their kittens off! Fine with me, I enjoy the game in a different way. However I don’t like the lags when I’m doing my events on my home server. That ruins my gaming experience. And I’m sure for many others as well!
Anet should not allow a system (guesting) that causes poorer gaming experience for other players. As it is now guesting is being abused AND causing a bad gaming experience for others.
The simple kittenion would be to reward each character ONE chest per event no matter how many servers the player visits. Then we could all enjoy playable events!