Mathy
I swear I have good sitting posture
Battles that have gone on for very many turns can lag one's browser a lot when first joining the battle -- the client must parse the entire battle log up to that point, after all. So it would be nice if before joining a battle that has gone on for X turns (X to be discussed) a popup would display:
The battle you are trying to join has gone on for 420 turns. Joining it may lag your browser.
(button: Proceed anyway)