Latency is dependent on distance to the server (among many things) and you can't compare LOL to Xsyon since they aren't on the same server.

To play Xsyon you need to make a wee jump over the atlantic ocean (figuratively speaking) and that jump is 90ms. Add some overhead and router delays and you end up on 150ms. So what you say is making sense, except for the thing about revenants. (they kill without hesitation and won't contribute to your overall latency - hahahaha, muhahahahahaha haha, hrm...)

I never experienced increased latency when being among players/animals/revenants. Are you sure it wasn't something else that made you "feel" like you had a 600ms ping?